Delve

For the league, see Delve league.

The subterranean chart of the Azurite Mine

A delve is the exploration of the nearly-infinite Azurite Mine dungeon. The character follows a Crawler (mine cart) powered by Voltaxic Sulphite through the mine to a checkpoint. Players can start delving from Act 4 onwards, when they reach The Mines and start encountering Niko, Master of the Depths.

Mechanics

The Azurite Mine consists of an infinite number of nodes. Each node has 1 to 4 paths connected to it, leading to nearby nodes. Each node has a checkpoint, a circle marked on the ground in a chamber at the center of the node. A node can be "cleared", meaning that the character can freely teleport to that node's checkpoint. Or it can be "uncleared", meaning that it is not accessible. The vast majority of nodes start out "uncleared".

In order to clear an uncleared node and receive its rewards, characters must perform delves. Each delve is an expedition along a path leading from a cleared node's checkpoint to an adjacent uncleared node's checkpoint. Along the way, the characters must follow the Crawler, fight or avoid large numbers of monsters, and beat an encounter at the uncleared node's checkpoint. If the players beat the encounter, they receive rewards, and the node is now cleared.

The difficulty and rewards of delves increase based on depth in the mine. Paths deeper below the surface contain higher-level monsters, but yield higher-level rewards as well.

Progress through the mine is shared among all a player's characters in a league; different leagues will have different Azurite Mines whose nodes must be cleared separately. When playing in parties, the whole party uses the party leader's Azurite Mine, and other party members cannot continue if the party leader leaves.

Mineshaft

When a player reaches the Azurite Mine for the first time in a given league (using any of their characters in that league) a single mineshaft entrance node is created. The mineshaft extends vertically downward from this initial entrance node based on the player's highest-level character in that league - the higher this level, the deeper the mineshaft extends. As of patch 3.16, Niko’s mineshaft will continue to extend deeper into the Azurite Mine, up to depth 101 by Character Level 90. The mineshaft, therefore, acts as a catch-up mechanic, allowing a character to access appropriately challenging depths even if the player has previously ignored the Delve mechanic.

When a new mineshaft node is created, it destroys any previously-existing node in the same spot. The mineshaft depth is shared by all of the player's characters in a league, and is based on the player's highest-level character in that league.

Subterranean Chart

Main page: Subterranean Chart

The Subterranean Chart screen lets the player see all nearby nodes in the Azurite Mine, teleport to and from the Mine Encampment, teleport to and from checkpoints in nodes that have already been cleared, and set up a delve from a cleared node to an uncleared node.

Crawler

The Crawler is used to provide the light needed to delve to undiscovered checkpoints. During a delve, the Crawler will automatically navigate along the path from the cleared node's checkpoint to the uncleared node's checkpoint, providing light around it. The Crawler's speed is based on the characters' movement speed. If characters move ahead of the Crawler, it will speed up to catch up to them; if characters fall behind the Crawler, it will slow or stop. Even though a delve's layout may provide multiple routes to the checkpoint, the Crawler will always follow a predetermined one; that means that players must be careful to follow the Crawler through junctions, since characters will be left in darkness if they take a different route than the Crawler.

The Crawler will also pick up items dropped within a large radius around it, which it drops when the checkpoint and encounter are cleared.

Voltaxic Generator

The Voltaxic Generator is a device located in the Mine Encampment at the entrance of the Azurite Mine. The Voltaxic Generator lets you permanently upgrade your character's Delve-related capabilities using Voltaxic Sulphite, as described below.

Sulphite

Voltaxic Sulphite -- usually just called Sulphite -- is a nontradable resource. It appears on the minimap as a golden yellow mineral . It is earned during play, and spent on Delve-related upgrades and resonators.

Every delve has a cost paid in Voltaxic Sulphite. The cost depends on the distance between the two nodes and the depth of the destination node. In order to start a delve, the player must have enough Sulphite to pay the full cost. But the cost is not paid all at once; instead, it is paid gradually as a Delve proceeds. This means that failed delves will often not cost the full original amount.

Sulphite is earned during play outside the mine. Starting with The Mines in Act 4, any zone instance can randomly contain Niko, Master of the Depths. These instances will include three caches of Sulphite. Clicking on a cache will summon Niko to harvest it, adding the Sulphite to that character's total, as well as to the total of nearby characters. The higher the instance's level, the more Sulphite is gained.

Sulphite can also be earned in maps. Selecting a Niko Atlas mission at the Map Device will guarantee that Niko and Sulphite caches appear in that map's instance. A Niko Atlas mission can also randomly occur if no Atlas mission is selected at the Map Device. A map instance's Sulphite total is increased by the map's item quantity bonus as well as by the map's level. Certain Scarabs can be used along with a map in the Map Device to guarantee a Niko encounter, and to increase a map instance's Sulphite rewards.

A character can only hold a limited amount of Sulphite at a time. A player can permanently upgrade a character's maximum Sulphite capacity at the Voltaxic Generator in the Mine Encampment using Azurite.

Sulphite Capacity ▾ [Expand] ▾

Upgrade Level	Sulphite Capacity	Cost
0	1,200	0
1	1,800	15
2	2,400	102
3	3,000	187
4	4,000	300
5	5,200	444
6	6,400	630
7	9,000	865
8	12,500	1,016
9	17,500	1,496
10	22,750	2,143
11	30,000	5,271
12	38,500	12,962
13	46,000	21,521
14	55,000	33,728
15	65,000	54,709

A player can use Azurite at the Voltaxic Generator to purchase various permanent upgrades to a character's Delve-related capabilities. These upgrades and their costs are discussed below. Note that the costs of some upgrades can become discounted if a player goes unusually long without buying them.

A player can also use Azurite to buy resonators from Niko, Master of the Depths at the Mine Encampment.

Sulphite scaling based on area level

Those are base values and can be further modified by map quantity. In maps, effective area level is used instead of base area level.

Sulphite Scaling ▾ [Expand] ▾

Area Level	Base Sulphite
2	10
3	10
4	11
5	11
6	11
7	13
8	14
9	14
10	14
11	14
12	16
13	18
14	18
15	18
16	19
17	19
18	21
19	21
20	21
21	23
22	23
23	24
24	24
25	24
26	26
27	27
28	27
29	27
30	29
31	29
32	31
33	31
34	31
35	32
36	32
37	34
38	34
39	34
40	35
41	35
42	37
43	37
44	37
45	39
46	40
47	40
48	40
49	42
50	42
51	43
52	43
53	43
54	45
55	45
56	47
57	47
58	47
59	48
60	50
61	50
62	50
63	50
64	52
65	53
66	53
67	53
68	68
69	137
70	209
71	282
72	356
73	433
74	510
75	591
76	671
77	755
78	840
79	927
80	1,016
81	1,106
82	1,198
83	1,291
84	1,383
85	1,476
86	1,568
87	1,568
88	1,568
89	1,568
90	1,568
91	1,568
92	1,568
93	1,568
94	1,568
95	1,568
96	1,568
97	1,568
98	1,568
99	1,568
100	1,568

Light and Darkness

Main page: Darkness

Light and darkness play a crucial role in delves. A character staying outside the light for long will almost certainly die.

Paths in the Azurite Mine are normally dark. Generic light radius modifiers will not work in the mine.

During delves, light is normally only present in a circular area around the Crawler. The deeper a delve goes into the mine, the more the Crawler's light radius is reduced. The game will warn the player if a character's light radius is particularly low due to depth.

The player can permanently upgrade a character's Crawler light radius at the Voltaxic Generator using Azurite.

Light Radius ▾ [Expand] ▾

Upgrade Level	Light Radius +%	Azurite
0	0	0
1	30	50
2	60	167
3	90	312
4	120	505
5	150	688
6	180	1,012
7	210	1,224
8	240	1,397
9	270	1,487
10	300	1,682
11	330	1,832
12	360	1,943
13	390	2,222
14	420	2,276
15	450	2,245
16	480	2,388
17	510	2,446
18	540	2,566
19	570	2,593
20	600	2,824
21	630	2,964
22	660	2,994
23	690	3,262
24	720	3,423
25	750	3,458
26	780	3,767
27	810	3,953
28	840	3,993
29	870	4,350
30	900	4,565
31	930	4,611
32	960	5,024
33	990	5,271
34	1,020	5,325
35	1,050	5,802
36	1,080	6,088
37	1,110	6,150
38	1,140	6,700
39	1,170	7,030
40	1,200	7,102
41	1,230	7,737
42	1,260	8,119
43	1,290	8,202
44	1,320	8,936
45	1,350	9,376
46	1,380	9,472
47	1,410	10,319
48	1,440	10,828
49	1,470	10,939
50	1,500	11,917
51	1,530	12,505
52	1,560	12,633
53	1,590	13,763
54	1,620	14,441
55	1,650	14,589
56	1,680	15,894
57	1,710	16,677
58	1,740	16,848
59	1,770	18,355
60	1,800	19,260
61	1,830	19,457
62	1,860	21,197
63	1,890	22,242
64	1,920	22,470
65	1,950	24,479
66	1,980	25,686
67	2,010	25,949
68	2,040	28,270
69	2,070	29,664
70	2,100	29,967
71	2,130	32,647
72	2,160	34,257
73	2,190	34,607
74	2,220	37,702
75	2,250	39,562
76	2,280	39,966
77	2,310	43,540
78	2,340	45,688
79	2,370	46,155
80	2,400	50,282
81	2,430	52,762
82	2,460	53,302
83	2,490	58,069
84	2,520	60,932
85	2,550	61,555
86	2,580	67,060
87	2,610	70,367
88	2,640	71,087
89	2,670	77,444
90	2,700	81,264
91	2,730	82,095
92	2,760	89,436
93	2,790	93,847
94	2,820	94,807
95	2,850	103,285
96	2,880	108,379
97	2,910	109,487
98	2,940	119,279
99	2,970	125,161
100	3,000	126,441
101	3,030	137,749
102	3,060	144,542
103	3,090	146,020
104	3,120	159,078
105	3,150	166,924

Stalkers, a monster found in Delves, can momentarily disable the Crawler's light source.

When a Delve is successfully completed, the Crawler will leave a permanent cable along the route taken by the Crawler during that Delve, permanently lighting that route along the path.

If a character moves outside of lit areas (whether during a Delve or not), the character rapidly begins taking damage from a stacking Darkness debuff. Stepping into a lit area clears the debuff. Allied minions and totems will not take darkness damage.

Darkness also affects combat. Monsters at the edge of the darkness take reduced damage, and monsters totally within the darkness cannot be damaged at all.

Darkness damage is not reduced by a character's elemental or Chaos resistances. Instead, the character has a separate darkness resistance, not shown on the character sheet but viewable at the Voltaxic Generator. The character's effective darkness resistance is reduced by the character's current depth in the mine. The game will warn the player if a character's effective damage resistance is particularly low due to depth.

The player can permanently upgrade a character's darkness resistance at the Voltaxic Generator using Azurite.

Darkness Resistance ▾ [Expand] ▾

Upgrade Level	Darkness Resistance +%	Azurite
0	0	0
1	30	101
2	60	261
3	90	451
4	120	719
5	150	1,021
6	180	1,379
7	210	1,658
8	240	1,808
9	270	2,077
10	300	2,259
11	330	2,377
12	360	2,721
13	390	2,970
14	420	2,929
15	450	3,116
16	480	3,191
17	510	3,148
18	540	3,429
19	570	3,599
20	600	3,635
21	630	3,961
22	660	4,156
23	690	4,198
24	720	4,574
25	750	4,799
26	780	4,848
27	810	5,282
28	840	5,543
29	870	5,599
30	900	6,100
31	930	6,401
32	960	6,466
33	990	7,044
34	1,020	7,392
35	1,050	7,467
36	1,080	8,135
37	1,110	8,537
38	1,140	8,624
39	1,170	9,395
40	1,200	9,858
41	1,230	9,959
42	1,260	10,850
43	1,290	11,385
44	1,320	11,501
45	1,350	12,530
46	1,380	13,148
47	1,410	13,282
48	1,440	14,470
49	1,470	15,184
50	1,500	15,339
51	1,530	16,711
52	1,560	17,535
53	1,590	17,714
54	1,620	19,298
55	1,650	20,250
56	1,680	20,457
57	1,710	22,287
58	1,740	23,386
59	1,770	23,625
60	1,800	25,738
61	1,830	27,007
62	1,860	27,283
63	1,890	29,723
64	1,920	31,189
65	1,950	31,508
66	1,980	34,326
67	2,010	36,018
68	2,040	36,387
69	2,070	39,641
70	2,100	41,596
71	2,130	42,021
72	2,160	45,779
73	2,190	48,037
74	2,220	48,528
75	2,250	52,868
76	2,280	55,475
77	2,310	56,042
78	2,340	61,054
79	2,370	64,065
80	2,400	64,720
81	2,430	70,508
82	2,460	73,985
83	2,490	74,742
84	2,520	81,426
85	2,550	85,442
86	2,580	86,315
87	2,610	94,035
88	2,640	98,672
89	2,670	99,681
90	2,700	108,595
91	2,730	113,951
92	2,760	115,116
93	2,790	125,411
94	2,820	131,596
95	2,850	132,942
96	2,880	144,831
97	2,910	151,973
98	2,940	153,527
99	2,970	167,257
100	3,000	175,506
101	3,030	177,300
102	3,060	193,156
103	3,090	202,682
104	3,120	204,755
105	3,150	223,066

Flares

Flares are consumable items that can be used to create a temporary lit area. Flare uses cannot be targeted; when used, the flare drops at the character's feet. Flares can only be used within the mine; they can be used whether or not a Delve is currently in progress.

Flares can be purchased at the Voltaxic Generator using Azurite, or found in Flare Caches during delves.

A character can only carry 3 Flares at first. The player can permanently upgrade a character's maximum Flare capacity, Flare light radius, and Flare duration at the Voltaxic Generator using Azurite.

Flare Carrying Capacity ▾ [Expand] ▾

Upgrade Level	Flares	Azurite
0	3	0
1	4	92
2	5	199
3	6	370
4	7	560
5	8	762
6	9	1,255
7	10	1,495
8	11	1,860
9	12	2,312
10	13	4,046
11	14	7,081
12	15	12,391
13	16	18,678
14	17	25,082
15	18	33,246
16	19	43,909
17	20	58,214

Flare Light Radius ▾ [Expand] ▾

Upgrade Level	Flare Radius +%	Azurite
0	0	0
1	30	121
2	60	233
3	90	396
4	120	598
5	150	850
6	180	1,111
7	210	1,273
8	240	1,385
9	270	1,576
10	300	1,714
11	330	1,811
12	360	2,072
13	390	2,235
14	420	2,205
15	450	2,345
16	480	2,402
17	510	2,369
18	540	2,581
19	570	2,709
20	600	2,736
21	630	2,981
22	660	3,128
23	690	3,160
24	720	3,443
25	750	3,612
26	780	3,649
27	810	3,976
28	840	4,172
29	870	4,215
30	900	4,591
31	930	4,818
32	960	4,867
33	990	5,302
34	1,020	5,564
35	1,050	5,621
36	1,080	6,123
37	1,110	6,425
38	1,140	6,491
39	1,170	7,072
40	1,200	7,420
41	1,230	7,496
42	1,260	8,167
43	1,290	8,569
44	1,320	8,657
45	1,350	9,431
46	1,380	9,896
47	1,410	9,998
48	1,440	10,892
49	1,470	11,429
50	1,500	11,546
51	1,530	12,578
52	1,560	13,199
53	1,590	13,334
54	1,620	14,526
55	1,650	15,242
56	1,680	15,398
57	1,710	16,775
58	1,740	17,603
59	1,770	17,783
60	1,800	19,373
61	1,830	20,328
62	1,860	20,536
63	1,890	22,373
64	1,920	23,476
65	1,950	23,716
66	1,980	25,837
67	2,010	27,111
68	2,040	27,388
69	2,070	29,838
70	2,100	31,309
71	2,130	31,629
72	2,160	34,458
73	2,190	36,157
74	2,220	36,527
75	2,250	39,794
76	2,280	41,756
77	2,310	42,183
78	2,340	45,956
79	2,370	48,222
80	2,400	48,715
81	2,430	53,072
82	2,460	55,689
83	2,490	56,258
84	2,520	61,290
85	2,550	64,312
86	2,580	64,970
87	2,610	70,780
88	2,640	74,271
89	2,670	75,030
90	2,700	81,740
91	2,730	85,771
92	2,760	86,648
93	2,790	94,398
94	2,820	99,053
95	2,850	100,066
96	2,880	109,015
97	2,910	114,391
98	2,940	115,561
99	2,970	125,895
100	3,000	132,104
101	3,030	133,455
102	3,060	145,390
103	3,090	152,560
104	3,120	154,120
105	3,150	167,903

Flare Duration ▾ [Expand] ▾

Upgrade Level	Flare Duration	Azurite
0	14	0
1	15	77
2	16	166
3	17	309
4	18	467
5	19	635
6	20	1,046
7	21	1,246
8	22	1,423
9	23	1,859
10	24	1,973

Dynamite

Dynamite is a consumable item used to destroy fractured walls. When used, a dynamite charge will detonate after a brief delay. The detonation will destroy any fractured wall within its blast radius, and deal area-of-effect damage to monsters within the blast radius.

Dynamite can be purchased using Azurite, or found in Dynamite Caches during Delves.

A character can only carry 3 dynamite charges at first. The player can upgrade the character's maximum dynamite capacity, dynamite blast radius, and dynamite area-of-effect damage at the Voltaxic Generator using Azurite.

Dynamite Carrying Capacity ▾ [Expand] ▾

Upgrade Level	Dynamite	Azurite
0	2	0
1	3	70
2	4	214
3	5	586
4	6	1,386
5	7	2,050

Dynamite Damage ▾ [Expand] ▾

Upgrade Level	Dynamite damage	Azurite
0	0	0
1	15	96
2	40	203
3	75	366
4	100	520
5	125	763
6	150	1,136
7	175	1,349
8	200	1,661
9	225	2,007
10	250	2,213

Dynamite Blast Radius ▾ [Expand] ▾

Upgrade Level	Dynamite Radius +%	Azurite
0	0	0
1	25	110
2	50	419
3	75	872
4	100	1,437
5	125	1,899

Instances

When a character enters the Azurite Mine, the game will normally spawn a new instance covering a 5x5 grid area around the character's location. If the instance is for a delve, it will always contain the full path that the delve will follow.

If a player currently has a mine instance created, the game will create a new instance and load the character into that instance in the following circumstances:

• The character teleports to a node outside the current instance.
• The player creates a delve that does not start at the Crawler's current location.
• The player creates a delve to an uncleared node outside the current instance.

Otherwise, the character will continue to use the current instance.

When a party leader creates a new mine instance, a portal to the instance will spawn for the other characters in the party to follow. If the party leader's character dies inside the instance, the portal's destination will move to the point where the character died.

Ordinarily, a character can always safely return to the same instance (rather than creating a new one) if the player clicks on the "Visit: The Mine" icon in the upper left corner of the Subterranean Chart. However, a solo player whose character dies in an instance can never return to that instance. That means that all items in the instance are lost.

Hidden Loot

Fossil Remains in darkness

The mines contain many themed chests, often hidden away in dark side areas along a path. These containers faintly sparkle, but their names do not display unless a character moves close to them.

They can contain items, fossils, resonators, flares, dynamite charges, or Azurite.

Locations

Biomes

Different areas of the Azurite Mine contain different biomes, shown with different colours on the Subterranean Chart. Different biomes have different appearances, different monsters, different possible encounters, and different common fossil drops. Rarely, a city biome will spawn, which contains better loot and rarely, a special boss; but these biomes contain more numerous and difficult monsters as well.

Image	Biome	Map Icon	Fossils by Rarity	Minimum Depth
				Depth	Weight
	Mines		Metallic FossilMetallic FossilStack Size: 20More Lightning modifiers No Physical modifiersPlace in a Resonator to influence item crafting. Shift click to unstack., Serrated FossilSerrated FossilStack Size: 20More Attack modifiers Fewer Caster modifiersPlace in a Resonator to influence item crafting. Shift click to unstack., Pristine FossilPristine FossilStack Size: 20More Life modifiers No Defence modifiersPlace in a Resonator to influence item crafting. Shift click to unstack., Aetheric FossilAetheric FossilStack Size: 20More Caster modifiers Fewer Attack modifiersPlace in a Resonator to influence item crafting. Shift click to unstack.	0	100
				40	100
				65	0
	Fungal Caverns		Dense FossilDense FossilStack Size: 20More Defence modifiers No Life ModifiersPlace in a Resonator to influence item crafting. Shift click to unstack., Aberrant FossilAberrant FossilStack Size: 20More Chaos modifiers No Lightning modifiersPlace in a Resonator to influence item crafting. Shift click to unstack., Perfect FossilPerfect FossilStack Size: 20Improved QualityPlace in a Resonator to influence item crafting. Shift click to unstack., Corroded FossilCorroded FossilStack Size: 20More Physical Ailment or Chaos Ailment modifiers No Elemental modifiersPlace in a Resonator to influence item crafting. Shift click to unstack., Gilded FossilGilded FossilStack Size: 10Item is overvalued by vendorsPlace in a Resonator to influence item crafting. Shift click to unstack.	4	0
				20	100
	Petrified Forest		Bound FossilBound FossilStack Size: 20More Minion, Aura or Curse modifiersPlace in a Resonator to influence item crafting. Shift click to unstack., Jagged FossilJagged FossilStack Size: 20More Physical modifiers No Chaos modifiersPlace in a Resonator to influence item crafting. Shift click to unstack., Corroded FossilCorroded FossilStack Size: 20More Physical Ailment or Chaos Ailment modifiers No Elemental modifiersPlace in a Resonator to influence item crafting. Shift click to unstack., Sanctified FossilSanctified FossilStack Size: 10Numeric modifier values are lucky High Level modifiers are more commonPlace in a Resonator to influence item crafting. Shift click to unstack.	4	0
				20	100
	Abyssal Depths		Aberrant FossilAberrant FossilStack Size: 20More Chaos modifiers No Lightning modifiersPlace in a Resonator to influence item crafting. Shift click to unstack., Bound FossilBound FossilStack Size: 20More Minion, Aura or Curse modifiersPlace in a Resonator to influence item crafting. Shift click to unstack., Gilded FossilGilded FossilStack Size: 10Item is overvalued by vendorsPlace in a Resonator to influence item crafting. Shift click to unstack., Lucent FossilLucent FossilStack Size: 20More Mana modifiers No Speed modifiersPlace in a Resonator to influence item crafting. Shift click to unstack.	10	0
				25	100
	Frozen Hollow		Frigid FossilFrigid FossilStack Size: 20More Cold modifiers No Fire modifiersPlace in a Resonator to influence item crafting. Shift click to unstack., Serrated FossilSerrated FossilStack Size: 20More Attack modifiers Fewer Caster modifiersPlace in a Resonator to influence item crafting. Shift click to unstack., Prismatic FossilPrismatic FossilStack Size: 20More Elemental modifiers No Physical Ailment or Chaos Ailment modifiersPlace in a Resonator to influence item crafting. Shift click to unstack., Sanctified FossilSanctified FossilStack Size: 10Numeric modifier values are lucky High Level modifiers are more commonPlace in a Resonator to influence item crafting. Shift click to unstack., Shuddering FossilShuddering FossilStack Size: 20More Speed modifiers No Mana modifiersPlace in a Resonator to influence item crafting. Shift click to unstack.	200	0
				40	100
	Magma Fissure		Scorched FossilScorched FossilStack Size: 20More Fire modifiers No Cold modifiersPlace in a Resonator to influence item crafting. Shift click to unstack., Prismatic FossilPrismatic FossilStack Size: 20More Elemental modifiers No Physical Ailment or Chaos Ailment modifiersPlace in a Resonator to influence item crafting. Shift click to unstack., Pristine FossilPristine FossilStack Size: 20More Life modifiers No Defence modifiersPlace in a Resonator to influence item crafting. Shift click to unstack., Deft FossilDeft FossilStack Size: 20More Critical modifiers No Attribute modifiersPlace in a Resonator to influence item crafting. Shift click to unstack., Fundamental FossilFundamental FossilStack Size: 20More Attribute modifiers No Critical modifiersPlace in a Resonator to influence item crafting. Shift click to unstack.	30	0
				50	100
	Sulphur Vents		Metallic FossilMetallic FossilStack Size: 20More Lightning modifiers No Physical modifiersPlace in a Resonator to influence item crafting. Shift click to unstack., Perfect FossilPerfect FossilStack Size: 20Improved QualityPlace in a Resonator to influence item crafting. Shift click to unstack., Aetheric FossilAetheric FossilStack Size: 20More Caster modifiers Fewer Attack modifiersPlace in a Resonator to influence item crafting. Shift click to unstack., Fundamental FossilFundamental FossilStack Size: 20More Attribute modifiers No Critical modifiersPlace in a Resonator to influence item crafting. Shift click to unstack.	55	0
				75	100
	Vaal Outpost		Unknown	33	0
				83	12
				600	18
	Abyssal City		Unknown	71	0
				83	4
				220	12
				600	18
	Primeval Ruins		Unknown	111	0
				220	4
				600	12

Weights

Current theory on weights:

The weight is scaled between the lower and upper entries based on current delve depth. See the table below for data mined values.

Example ▾ [Expand] ▾

Depth	Weight
50	0
100	100

If your character is below or at depth 50, the biome will not spawn.

If your character is between 50 and 100, the biome will spawn and the weight will increase accordingly;

Depth 51, 2 weight

Depth 52, 4 weight

...

Depth 99, 98 weight

Depth 100, 100 weight

If your character is below depth 100, the biome will always have a weight of 100

Nodes

Biome Specific Nodes: source: wiki editor's observation and poedb

Icon	Node name	Description	Biome	Footnotes
	Haunted Tomb	Contains Fossils	Fungal Caverns only	Contains Tangled FossilTangled FossilStack Size: 10Makes a random modifier type much more likely and prevents another random modifier type. Effects revealed once resonator is fully socketed.Place in a Resonator to influence item crafting. Shift click to unstack.
	Stonewood Hollow	Contains Fossils	Petrified Forest only	Contains Bloodstained FossilBloodstained FossilStack Size: 10Corrupted Has a Corrupted implicit modifierPlace in a Resonator to influence item crafting. Shift click to unstack.
	Crystal Spire	Contains Fossils	Abyssal Depths only	Contains Hollow FossilHollow FossilStack Size: 10Has an Abyssal socketPlace in a Resonator to influence item crafting. Shift click to unstack.
	Time-Lost Cavern	Contains Fossils	Frozen Hollow only	Contains Glyphic FossilGlyphic FossilStack Size: 10Has a Corrupt Essence modifierPlace in a Resonator to influence item crafting. Shift click to unstack.
	Molten Cavity	Contains Fossils	Magma Fissure only	Contains Faceted FossilFaceted FossilStack Size: 10More Gem modifiersPlace in a Resonator to influence item crafting. Shift click to unstack.
	Humid Fissure	Contains Fossils	Sulphur Vents only	Contains Fractured FossilFractured FossilStack Size: 10Creates a split copy. Cannot be used to split Influenced, Enchanted, Fractured, or Synthesised items.Place in a Resonator to influence item crafting. Shift click to unstack.
	Ruined Chamber	Contents Unknown	Vaal Outpost only	Contains Vaal Ruined Chamber which has multiple loot containers
	The Grand Architect's Temple	Contents Unknown	Vaal Outpost only	Contains Ahuatotli, the Blind.
	Haunted Remains	Contains Abyss Items	Abyssal Depths only	Haunted Remains has generic drop version
	Unspeakable Shrine	Contains Abyss Items	Abyssal Depths only
	Abyssal Chamber	Contents Unknown	Abyssal City only	Contains Abyssal Chamber which has multiple loot containers
	The Lich's Tomb	Contents Unknown	Abyssal City only	Contains Kurgal, the Blackblooded.
	Primeval Chamber	Contents Unknown	Primeval Ruins only	Contains Primeval Chamber which has multiple loot containers
	The Crystal King's Throne	Contents Unknown	Primeval Ruins only	Contains Aul, the Crystal King.
	Prospero's Deposit	Contents Unknown	Magma Fissure only	Contains Perandus CoinsPerandus CoinStack Size: 5000Trade coins to Cadiro Perandus. Shift click to unstack..
	Echoing Lair	Contains Animalistic items	Fungal Caverns only	Contains beasts as bosses
	Ritual Grounds	Contains Talismans	Petrified Forest only	Contains Talisman-possessed monsters are bosses
	Frigid Recess	Contains Essences	Frozen Hollow only	Frigid Recess has generic drop version
	Redblade Retreat or Redblade Base	Contains Fire Items	Magma Fissure only	Contains Redblade Warbands as bosses.
	Mutewind Retreat or Mutewind Base	Contains Cold Items	Frozen Hollow only	Contains Mutewind Warbands as bosses
	Brinerot Retreat or Brinerot Base	Contains Lightning Items	Sulphur Vents only	Contains Brinerot Warbands as bosses
	Renegade Camp	Contains Chaos Items	Fungal Caverns only	Contains Renegades Warbands as bosses
	Restless Rubble or Sweltering Burrow	Contains Fire Items	Magma Fissure only	Both nodes have generic drop versions
	Restless Rubble or Frigid Recess	Contains Cold Items	Frozen Hollow only	Both nodes have generic drop versions
	Restless Rubble	Contains Lightning Items	Sulphur Vents only	Restless Rubble has generic drop version
	Restless Rubble	Contains Chaos Items	Fungal Caverns only	Restless Rubble has generic drop version
	Nesting Grounds	Contains Physical Items	Petrified Forest only	Nesting Grounds has generic drop version
	Haunted Remains	Contains Mana or Curse Items	Abyssal Depths only	Haunted Remains has generic drop version
	Necromancer's Excavation	Contains Minion or Aura Items	Abyssal Depths or Fungal Caverns only	Necromancer's Excavation also have generic loot versions
	Grim Copse	Contains Minion or Aura Items	Petrified Forest only	Grim Copse also has generic loot version
	Beast Burrow	Contains Minion or Aura Items	Fungal Caverns only	Beast Burrow also has generic loot version

Common Nodes:

Main page: List of Delve nodes

Icon	Node name	Description	Footnotes
	Azurite Cavity	Contains Azurite	Contains a small amount of Azurite.
	Azurite Vault	Contains Azurite	Contains a medium amount of Azurite.
	Azurite Fissure	Contains Azurite	Contains a large amount of Azurite.
	variable	Contains Items	Contains assorted items.
	variable	Contains Weapons
	variable	Contains Armour	Contains armour: body armour, helmet, boot, glove, etc.
	variable	Contains Jewellery
	variable	Contains Currency	Contains base currencies
	variable	Contains Gems
	variable	Contains Maps
	Underground Stash	Contains Strongboxes
	Runed Cavern	Contains a Harbinger
	Whispering Gallery	Contains a Breach
	Pulsating Grotto	Contains Monsters from Beyond
	Buried Monolith	Contains a Legion encounter
variable	Smuggler's Stash	variable	Contains generic loots
	Smuggler's Stash	Contains Fossils	Contains less valuable generic fossils only

Depth Scaling ▾ [Expand] ▾

Sulphite cost caps at 1100 at depth 890 and beyond.

There is additional scaling starting at depth 1600, which caps out at around depth 2586.

Depth	Monster Level	Base Sulphite Cost	Darkness Resistance & Light Radius	More Monster Life	More Monster Damage
1	34	21	0	0	0
2	35	24	0	0	0
3	36	24	-2	0	0
4	37	24	-4	0	0
5	38	27	-6	0	0
6	39	27	-8	0	0
7	40	28	-10	0	0
8	41	29	-12	0	0
9	42	29	-14	0	0
10	43	29	-16	0	0
11	44	29	-18	0	0
12	45	31	-20	0	0
13	46	34	-22	0	0
14	47	37	-24	0	0
15	48	37	-26	0	0
16	49	37	-28	0	0
17	50	39	-30	0	0
18	51	40	-32	0	0
19	52	41	-34	0	0
20	53	43	-36	0	0
21	54	43	-38	0	0
22	55	45	-40	0	0
23	56	47	-42	0	0
24	57	47	-44	0	0
25	58	49	-46	0	0
26	59	51	-48	0	0
27	60	51	-50	0	0
28	61	53	-52	0	0
29	62	55	-54	0	0
30	63	55	-56	0	0
31	64	57	-58	0	0
32	65	59	-60	0	0
33	66	61	-62	0	0
34	67	62	-64	0	0
35	68	77	-66	0	0
36	68	77	-68	0	0
37	68	77	-70	0	0
38	68	77	-72	0	0
39	69	77	-74	0	0
40	69	77	-76	0	0
41	69	112	-78	0	0
42	69	112	-80	0	0
43	70	112	-82	0	0
44	70	112	-84	0	0
45	70	112	-86	0	0
46	70	112	-88	0	0
47	71	147	-90	0	0
48	71	147	-92	0	0
49	71	147	-94	0	0
50	71	147	-96	0	0
51	72	147	-98	0	0
52	72	147	-100	0	0
53	72	182	-102	0	0
54	72	182	-104	0	0
55	73	182	-106	0	0
56	73	182	-108	0	0
57	73	182	-110	0	0
58	73	182	-112	0	0
59	74	217	-114	0	0
60	74	217	-116	0	0
61	74	217	-118	0	0
62	74	217	-120	0	0
63	74	217	-122	0	0
64	75	217	-124	0	0
65	75	253	-126	0	0
66	75	253	-128	0	0
67	75	253	-130	0	0
68	75	253	-132	0	0
69	76	253	-134	0	0
70	76	253	-136	0	0
71	76	253	-138	0	0
72	76	253	-140	0	0
73	76	253	-142	0	0
74	77	288	-144	0	0
75	77	288	-146	0	0
76	77	288	-148	0	0
77	77	288	-150	0	0
78	77	288	-152	0	0
79	77	288	-154	0	0
80	77	288	-156	0	0
81	78	288	-158	0	0
82	78	288	-160	0	0
83	78	323	-162	0	0
84	78	323	-164	0	0
85	78	323	-166	0	0
86	78	323	-168	0	0
87	78	323	-170	0	0
88	78	323	-172	0	0
89	78	323	-174	0	0
90	79	323	-176	0	0
91	79	323	-178	0	0
92	79	358	-180	0	0
93	79	358	-182	0	0
94	79	358	-184	0	0
95	79	358	-186	0	0
96	79	358	-188	0	0
97	79	358	-190	0	0
98	79	358	-192	0	0
99	79	358	-194	0	0
100	79	358	-196	0	0
101	80	393	-198	0	0
102	80	393	-200	0	0
103	80	393	-202	0	0
104	80	393	-204	0	0
105	80	393	-206	0	0
106	80	393	-208	0	0
107	80	393	-209	0	0
108	80	393	-210	0	0
109	80	393	-211	0	0
110	80	429	-212	0	0
111	80	429	-213	0	0
112	80	429	-214	0	0
113	80	429	-215	0	0
114	81	429	-216	0	0
115	81	429	-217	0	0
116	81	429	-218	0	0
117	81	429	-219	0	0
118	81	429	-220	0	0
119	81	429	-221	0	0
120	81	429	-222	0	0
121	81	429	-223	0	0
122	81	482	-224	0	0
123	81	482	-225	0	0
124	81	482	-226	0	0
125	81	482	-227	0	0
126	81	482	-228	0	0
127	81	482	-229	0	0
128	81	482	-230	0	0
129	82	482	-231	0	0
130	82	482	-232	0	0
131	82	482	-233	0	0
132	82	482	-234	0	0
133	82	482	-235	0	0
134	82	536	-236	0	0
135	82	536	-237	0	0
136	82	536	-238	0	0
137	82	536	-239	0	0
138	82	536	-240	0	0
139	82	536	-241	0	0
140	82	536	-242	0	0
141	82	536	-243	0	0
142	82	536	-244	0	0
143	82	536	-245	0	0
144	82	536	-246	0	0
145	83	536	-247	0	0
146	83	589	-248	10	1
147	83	589	-249	11	1
148	83	589	-250	11	1
149	83	589	-251	12	1
150	83	589	-252	12	1
151	83	589	-253	13	1
152	83	589	-254	14	1
153	83	589	-255	14	1
154	83	589	-256	15	1
155	83	589	-257	15	1
156	83	589	-258	15	1
157	83	589	-259	16	1
158	83	589	-260	16	1
159	83	643	-261	17	1
160	83	643	-262	17	1
161	83	643	-263	18	1
162	83	643	-264	18	1
163	83	643	-265	19	1
164	83	643	-266	19	1
165	83	643	-267	20	1
166	83	643	-268	20	1
167	83	643	-269	21	1
168	83	643	-270	21	1
169	83	643	-271	22	1
170	83	643	-272	23	1
171	83	697	-273	23	1
172	83	697	-274	24	1
173	83	697	-275	24	1
174	83	697	-276	25	1
175	83	697	-277	26	1
176	83	697	-278	26	1
177	83	698	-279	27	1
178	83	698	-280	28	1
179	83	699	-281	28	1
180	83	699	-282	29	1
181	83	700	-283	30	1
182	83	700	-284	30	1
183	83	701	-285	31	1
184	83	701	-286	32	1
185	83	702	-287	32	1
186	83	702	-288	33	1
187	83	703	-289	34	1
188	83	703	-290	35	1
189	83	704	-291	35	1
190	83	704	-292	36	1
191	83	705	-293	37	1
192	83	705	-294	38	1
193	83	706	-295	38	2
194	83	706	-296	39	2
195	83	707	-297	40	2
196	83	707	-298	41	2
197	83	708	-299	42	2
198	83	708	-300	43	2
199	83	709	-301	43	2
200	83	709	-302	44	2
201	83	710	-303	45	2
202	83	710	-304	46	2
203	83	711	-305	47	2
204	83	711	-306	48	2
205	83	712	-307	49	2
206	83	712	-308	50	2
207	83	713	-309	51	2
208	83	713	-310	52	2
209	83	714	-311	53	2
210	83	714	-312	53	2
211	83	715	-313	54	2
212	83	715	-314	55	2
213	83	716	-315	56	2
214	83	716	-316	57	2
215	83	717	-317	58	2
216	83	717	-318	59	2
217	83	718	-319	60	2
218	83	718	-320	62	2
219	83	719	-321	63	2
220	83	719	-322	64	2
221	83	720	-323	65	2
222	83	720	-324	66	2
223	83	721	-325	67	2
224	83	721	-326	68	2
225	83	722	-327	69	2
226	83	722	-328	70	2
227	83	723	-329	71	3
228	83	723	-330	72	3
229	83	724	-331	74	3
230	83	724	-332	75	3
231	83	725	-333	76	3
232	83	725	-334	77	3
233	83	726	-335	78	3
234	83	726	-336	79	3
235	83	727	-337	81	3
236	83	727	-338	82	3
237	83	728	-339	83	3
238	83	728	-340	84	3
239	83	729	-341	85	3
240	83	729	-342	87	3
241	83	730	-343	88	3
242	83	730	-344	89	3
243	83	731	-345	91	3
244	83	731	-346	92	3
245	83	732	-347	93	3
246	83	732	-348	94	3
247	83	733	-349	96	3
248	83	733	-350	97	3
249	83	734	-351	98	3
250	83	734	-352	100	4
251	83	735	-353	101	4
252	83	735	-354	102	4
253	83	736	-355	104	4
254	83	736	-356	105	4
255	83	737	-357	107	4
256	83	737	-358	108	4
257	83	738	-359	109	4
258	83	738	-360	111	4
259	83	739	-361	112	4
260	83	740	-362	114	4
261	83	740	-363	115	4
262	83	741	-364	117	4
263	83	741	-365	118	4
264	83	742	-366	120	4
265	83	742	-367	121	4
266	83	743	-368	123	4
267	83	743	-369	124	4
268	83	744	-370	126	4
269	83	744	-371	127	5
270	83	745	-372	129	5
271	83	745	-373	130	5
272	83	746	-374	132	5
273	83	746	-375	133	5
274	83	747	-376	135	5
275	83	747	-377	136	5
276	83	748	-378	138	5
277	83	748	-379	140	5
278	83	749	-380	141	5
279	83	749	-381	143	5
280	83	750	-382	145	5
281	83	750	-383	146	5
282	83	751	-384	148	5
283	83	752	-385	149	5
284	83	752	-386	151	5
285	83	753	-387	153	5
286	83	753	-388	155	6
287	83	754	-389	156	6
288	83	754	-390	158	6
289	83	755	-391	160	6
290	83	755	-392	161	6
291	83	756	-393	163	6
292	83	756	-394	165	6
293	83	757	-395	167	6
294	83	757	-396	168	6
295	83	758	-397	170	6
296	83	758	-398	172	6
297	83	759	-399	174	6
298	83	759	-400	176	6
299	83	760	-401	177	6
300	83	760	-402	179	6
301	83	761	-403	181	7
302	83	762	-404	183	7
303	83	762	-405	185	7
304	83	763	-406	187	7
305	83	763	-407	188	7
306	83	764	-408	190	7
307	83	764	-409	192	7
308	83	765	-410	194	7
309	83	765	-411	196	7
310	83	766	-412	198	7
311	83	766	-413	200	7
312	83	767	-414	202	7
313	83	767	-415	204	7
314	83	768	-416	206	8
315	83	769	-417	208	8
316	83	769	-418	210	8
317	83	770	-419	212	8
318	83	770	-420	214	8
319	83	771	-421	216	8
320	83	771	-422	218	8
321	83	772	-423	220	8
322	83	772	-424	222	8
323	83	773	-425	224	8
324	83	773	-426	226	8
325	83	774	-427	228	8
326	83	774	-428	230	8
327	83	775	-429	232	9
328	83	776	-430	234	9
329	83	776	-431	236	9
330	83	777	-432	238	9
331	83	777	-433	240	9
332	83	778	-434	243	9
333	83	778	-435	245	9
334	83	779	-436	247	9
335	83	779	-437	249	9
336	83	780	-438	251	9
337	83	780	-439	253	9
338	83	781	-440	256	10
339	83	782	-441	258	10
340	83	782	-442	260	10
341	83	783	-443	262	10
342	83	783	-444	264	10
343	83	784	-445	267	10
344	83	784	-446	269	10
345	83	785	-447	271	10
346	83	785	-448	273	10
347	83	786	-449	276	10
348	83	786	-450	278	10
349	83	787	-451	280	11
350	83	788	-452	283	11
351	83	788	-453	285	11
352	83	789	-454	287	11
353	83	789	-455	290	11
354	83	790	-456	292	11
355	83	790	-457	294	11
356	83	791	-458	297	11
357	83	791	-459	299	11
358	83	792	-460	301	11
359	83	793	-461	304	11
360	83	793	-462	306	12
361	83	794	-463	309	12
362	83	794	-464	311	12
363	83	795	-465	313	12
364	83	795	-466	316	12
365	83	796	-467	318	12
366	83	796	-468	321	12
367	83	797	-469	323	12
368	83	798	-470	326	12
369	83	798	-471	328	12
370	83	799	-472	331	13
371	83	799	-473	333	13
372	83	800	-474	336	13
373	83	800	-475	338	13
374	83	801	-476	341	13
375	83	801	-477	343	13
376	83	802	-478	346	13
377	83	803	-479	348	13
378	83	803	-480	351	13
379	83	804	-481	354	14
380	83	804	-482	356	14
381	83	805	-483	359	14
382	83	805	-484	361	14
383	83	806	-485	364	14
384	83	807	-486	367	14
385	83	807	-487	369	14
386	83	808	-488	372	14
387	83	808	-489	375	14
388	83	809	-490	377	15
389	83	809	-491	380	15
390	83	810	-492	383	15
391	83	811	-493	385	15
392	83	811	-494	388	15
393	83	812	-495	391	15
394	83	812	-496	394	15
395	83	813	-497	396	15
396	83	813	-498	399	15
397	83	814	-499	402	16
398	83	814	-500	405	16
399	83	815	-501	407	16
400	83	816	-501	410	16
401	83	816	-502	413	16
402	83	817	-502	416	16
403	83	817	-503	418	16
404	83	818	-503	421	16
405	83	818	-504	424	16
406	83	819	-504	427	17
407	83	820	-505	430	17
408	83	820	-505	433	17
409	83	821	-506	436	17
410	83	821	-506	438	17
411	83	822	-507	441	17
412	83	822	-507	444	17
413	83	823	-508	447	17
414	83	824	-508	450	18
415	83	824	-509	453	18
416	83	825	-509	456	18
417	83	825	-510	459	18
418	83	826	-510	462	18
419	83	827	-511	465	18
420	83	827	-511	468	18
421	83	828	-512	471	18
422	83	828	-512	474	19
423	83	829	-513	477	19
424	83	829	-513	480	19
425	83	830	-514	483	19
426	83	831	-514	486	19
427	83	831	-515	489	19
428	83	832	-515	492	19
429	83	832	-516	495	19
430	83	833	-516	498	20
431	83	834	-517	501	20
432	83	834	-517	504	20
433	83	835	-518	507	20
434	83	835	-518	510	20
435	83	836	-519	514	20
436	83	836	-519	517	20
437	83	837	-520	520	21
438	83	838	-520	523	21
439	83	838	-521	526	21
440	83	839	-521	529	21
441	83	839	-522	532	21
442	83	840	-522	536	21
443	83	841	-523	539	21
444	83	841	-523	542	21
445	83	842	-524	545	22
446	83	842	-524	549	22
447	83	843	-525	552	22
448	83	843	-525	555	22
449	83	844	-526	558	22
450	83	845	-526	562	22
451	83	845	-527	565	22
452	83	846	-527	568	23
453	83	846	-528	571	23
454	83	847	-528	575	23
455	83	848	-529	578	23
456	83	848	-529	581	23
457	83	849	-530	585	23
458	83	849	-530	588	23
459	83	850	-531	591	24
460	83	851	-531	595	24
461	83	851	-532	598	24
462	83	852	-532	601	24
463	83	852	-533	605	24
464	83	853	-533	608	24
465	83	854	-534	612	24
466	83	854	-534	615	25
467	83	855	-535	618	25
468	83	855	-535	622	25
469	83	856	-536	625	25
470	83	857	-536	629	25
471	83	857	-537	632	25
472	83	858	-537	636	26
473	83	858	-538	639	26
474	83	859	-538	643	26
475	83	860	-539	646	26
476	83	860	-539	650	26
477	83	861	-540	653	26
478	83	861	-540	657	26
479	83	862	-541	660	27
480	83	863	-541	664	27
481	83	863	-542	667	27
482	83	864	-542	671	27
483	83	864	-543	675	27
484	83	865	-543	678	27
485	83	866	-544	682	28
486	83	866	-544	685	28
487	83	867	-545	689	28
488	83	867	-545	693	28
489	83	868	-546	696	28
490	83	869	-546	700	28
491	83	869	-547	704	28
492	83	870	-547	707	29
493	83	870	-548	711	29
494	83	871	-548	715	29
495	83	872	-549	718	29
496	83	872	-549	722	29
497	83	873	-550	726	29
498	83	874	-550	729	30
499	83	874	-551	733	30
500	83	875	-551	737	30

More...

Fractured walls and hidden paths

Fractured Wall

Fractured Wall Mini-map Icon with Hidden Room

Some nodes on the Subterranean Chart will have no paths shown leading to them. This means that the path to that node is hidden. These hidden paths are blocked by a fractured wall somewhere in the darkness along a side route from a nearby node. Destroying this fractured wall will permanently reveal the path to the hidden node on the Subterranean Chart, and the player can now start a delve to the previously-isolated node.

In addition, normal paths can contain fractured walls leading to hidden side areas containing monsters and loot containers.

Fractured walls and the areas behind them will not normally appear on the minimap. However, if a character moves close enough, an icon will appear in the player's minimap for as long as the character remains in range. Fractured walls can be destroyed using dynamite. A dynamite charge will destroy any fractured wall within its blast radius.

Finding hidden paths to isolated nodes

To find hidden paths more easily, you need to first figure out the grid for your map. Once you have it, the first rule to apply is: Fractured walls can only appear in grid spaces not occupied by a node. If two nodes are in adjacent grid spaces, there cannot be a fractured wall along the short path between them.

Once you know where the fractured wall can be, use the following rules:

• A node will almost always have 1, 3, or 4 paths connecting to it. A node with exactly 2 connecting paths only occurs occasionally, when the mine layout generator tries to create a path that is too long. This means that if a node is shown on the Subterranean Chart with exactly 2 paths leading from it, that node will nearly always have a fractured wall blocking a third, hidden path to a nearby isolated node.
• It is possible, though rare, for an apparent dead-end node -- a node with only one visible path connecting to it -- to have two hidden paths leading to two different nearby isolated nodes.
• Paths never overlap with each other, and they never intersect (other than at nodes). If the space between a visible node and a nearby isolated node is already occupied by a path, there cannot be a hidden path between those nodes.
• A node cannot have more than one path leading away in a given cardinal direction. If there is already a visible path heading in one direction from a node, there cannot be a hidden path heading in that same direction.
• There will always be at least one fractured wall in grids that do not contain checkpoints.

Major Bosses

A city biome may contain a special boss. Each boss can only spawn below a certain minimum depth.

Boss	Biome	Depth
Ahuatotli, the Blind	Vaal Outpost	50
Kurgal, the Blackblooded	Abyssal City	90
Aul, the Crystal King	Primeval Ruins	130

Minor bosses

There are other minor unique bosses for other Delve nodes, such as:

Boss	Node	Biome
Miner's Grip Awoken Giant	Haunted Tomb	Fungal Caverns
Gehennix	Molten Cavity	Magma Fissure
Priest of the Blood Covenant	Stonewood Hollow	Petrified Forest
Petrification Statue	Humid Fissure	Sulphur Vents
5 Rogue Exiles	Smuggler's Stash	any biome
Amplifier Defender	Abandoned Amplifier	Mines
Captain Stuart "Stab-First" Grenn	Frigid Recess	Frozen Hollow
Magmatic Golem	Restless Rubble (Magma Fissure version only)	Magma Fissure
Golem	Restless Rubble	any other biome
Primordial Beast	Beast Burrow	Fungal Caverns
Lion of the Tunnels or Gorgol Terror or Blackhowl, Prime Stalker	Azurite Fissure
Diabolic Whisperer	Necromancer's Excavation	Abyssal Depths or Fungal Caverns
Diabolic Whisperer	Grim Copse	Petrified Forest

Lore

Delve was released in the Delve league, see that page for more details.

Version history

Version	Changes
3.21.0	Added a series of new "Profane" modifiers that can roll on Maps, Logbooks, Delve Biomes, and Heist Contracts. These modifiers cause Monsters to deal extra Physical Damage as Chaos and cause Monsters to Inflict Withered for 2 seconds on Hit.
3.17.0	Introduced new modifiers that can roll on Maps, Expedition Logbooks, Heist Contracts, Blueprints and Delve areas. Shields that drop from Delve Chests no longer have their own maximum Resistances prefix modifiers. Changed Delve biome modifiers that forced chests in side passages to be a particular chest to instead only affect chests behind fractured walls. Modifiers that made side passage chests of a particular type remain unchanged. Reduce the values of sulphite-used biome modifiers: They now range from 20-50% reduced sulphite used, down from 25-100% reduced. Higher values of this mod can now also only appear deeper in the mines, with the highest tier becoming available at depth 500+.
3.16.0	The difficulty of Delve encounters now scales much faster. The difficulty of encounters at depth 500 is now roughly equivalent to the previous difficulty of depth 1,000 encounters. Depth 1,500 encounters are now roughly equivalent to the previous difficulty of depth 6,000 encounters. The availability of rewards from Delve also now scales much faster, with the intention that progressing deeper into the Azurite Mine is more rewarding than equivalent depths previously were. For example, depth 500 is now more rewarding than depth 1,000 was previously. As a result of these changes, the Azurite Mine has been reset in Permanent Leagues. Niko has drilled a mineshaft to the deepest level Delve encounter previously completed in that league to pick up where you left off. This change does not affect gathered Azurite or Sulphite, or upgrades you have purchased at the Voltaxic Generator. Previously-acquired Delve depth and solo depth has been wiped from the Permanent League ladders. To get back on the ladder, just keep playing Delve from whatever level you can handle. City Biomes in the Azurite Mine are now more common and can appear in earlier depths, but are now smaller on average. City Biomes can no longer spawn without Delve nodes. We've also introduced new Delve Biome modifiers, and allowed Delve Biome modifiers to spawn below depth 6,000. The Area Level of the Azurite Mine now scales slightly faster, reaching Area Level 83 at depth 145 (previously depth 171). Niko's mineshaft can now drill deeper into the Azurite Mine, up to depth 101 by Character Level 90. Delve encounters now contain fewer chests, though each chest is now more likely to drop interesting rewards. Increased the base Sulphite Capacity to 1,200 (previously 600), scaling up to 6,400 Capacity after six upgrades (unchanged). The damage dealt by the Darkness based on player Life and Energy Shield has been roughly halved. The flat damage per Darkness stack now scales with depth, up to a cap at around depth 1,000. For an example of the impact this has, a character with 6,000 Life would take less damage from the Darkness than previously at depths below about 500, and take approximately 50% more damage from the Darkness at depth 1,000 and greater. A character with extremely low amounts of Life could take as much as ten times the Darkness damage it previously did at depth 1,000. Introduced a new type of Spider enemy that drops from the ceiling and uses Flicker StrikeFlicker StrikeAttack, Melee, Strike, Movement, Duration Level: (1-20) Cost: 10 Mana Cooldown Time: 2.00 sec Can Store 1 Use(s) Attack Speed: 120% of base Attack Damage: (142-210)% of base Effectiveness of Added Damage: (142-210)%Requires Level 10Teleports the character to a nearby monster and attacks with a melee weapon. If no specific monster is targeted, one is picked at random. Grants a buff that increases movement speed for a duration. The cooldown can be bypassed by expending a Frenzy Charge.Base duration is 3 seconds 10% increased Attack Speed per Frenzy Charge 15% chance to gain a Frenzy Charge on Hit Buff grants 20% increased Movement Speed Additional Effects per 1% Quality: 0.25% chance to gain a Frenzy Charge on HitPlace into an item socket of the right colour to gain this skill. Right click to remove from a socket. Monsters in Darkness now attack players from 50 units away (previously 20). Assorted changes to monster-specific behavior (refer to actual patch notes for these).
3.13.0	Maps dropped by special sources such as deterministic chests or league rewards like those found in the Azurite Mine or the Temple of Atzoatl now use your own Atlas to determine which maps to drop, and can therefore drop maps that have been raised above their base tier due to the presence of Watchstones. Maps dropped from these sources now also take into account your Favourite Map selections. If a source such as this cannot find a compatible map from your Atlas to drop (for example, due to too few maps being completed and too few watchstones being socketed for a Tier 16 map on your Atlas to drop), it will drop a random map of the correct tier instead.
3.12.4d	The Azurite Mine is now capped at Depth Level 65,535.
3.8.0	Your Voltaxic Sulphite is now shared across all characters on the same account and in the same league. There is still a hard upper limit of 65000 Sulphite. Characters that are merged to Standard at the end of a league will bring their Sulphite with them, up to whatever your highest maximum Sulphite limit is. The tunnel Niko digs for you based on your character level is now also shared league-wide across all your characters, meaning your highest-level character will determine the depth of Niko's tunnel for all characters. This tunnel will only ever, at most, be 6 levels behind your highest-level character until you reach level 68. Previously, it was 15 levels behind by the time you reach level 68. The rate of level growth for monsters within the Azurite Mine is now faster, requiring significantly fewer depths to hit the maximum monster levels within the Mine. This was because most players progressed through the Atlas faster than the Mine, and the two difficulty levels would quickly become out of sync. As a result of the change to the depth-to-level ratio, the cost of Delves in those interim levels has been increased, but tapers back to the original costs as you get deeper. You can now find Legion encounters and rewards in the Azurite Mine.
3.4.0	Introduced to the game in the Delve leagues.