Cast when Damage Taken Support

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Cast when Damage Taken is a support gem. It causes a linked spell to trigger when the player takes a certain amount of damage.

Skill functions and interactions

Trigger gem: Like all trigger gems, Cast when Damage Taken only "casts" spells. Attack gems such as Double Strike are not considered spells. Multiple spells can be linked to a single trigger gem, and will all be triggered if so. Multiple copies of Cast when Damage Taken will also function independently.

Damage counter and cooldown: Each linked spell gains an internal damage counter that tracks the total accumulated damage taken from hits, though not from damage over time or the Blood Magic passive^[1] (e.g. you cannot use Module Error: Too many skills found with q_where = skill.active_skill_name="Righteous Fire". Please choose only one of the following ids:
MonsterRighteousFireDemonBoss - Deals (1.9-647.8) Base Fire Damage per second, Base radius is 1.8 metres (page)
WickerManRighteousFireBlight - Deals 1.3 Base Fire Damage per second, Base radius is 1.8 metres (page) to trigger Cast when Damage Taken). All damage counters will be reset to 0 upon entering a new area. When a linked spell is cast, it is put on cooldown for 250 ms and will not track damage during that time.

Multiple copies of the same gem share cooldowns, meaning that if two copies of the same spell are triggered within 250 ms of each other, the first will trigger and the second will fail to do so as it is on cooldown. This mostly prevents using multiple copies of the same spell with Cast when Damage Taken, though the use of Cast when Damage Taken gems of different levels can avoid cooldown overlap in some circumstances due to the differing amounts of damage required to trigger the spells.

The Cast when Damage Taken gem itself does not have its own counter or cooldown^[2].

Maximum level of supported skills: Cast when Damage Taken cannot support skills with a higher player level requirement than that of Cast when Damage Taken itself. Note that this restriction only applies to active skills; any level of other support gems may be used.

Trigger order: Trigger gems and their linked skills are cast in a certain order that depends both on which item it is equipped on and which socket the skills are in. If there are trigger gems in each equipped item, the order of operation will be:

Main hand ⇒ Amulet ⇒ Helm ⇒ Off hand ⇒ Body armour ⇒ Gloves ⇒ Boots

The linked sockets also follow a specific order, as follows:

1	⇒	2
		⇓
4	⇐	3
⇓
5	⇒	6

Damage effectiveness: The damage effectiveness increases with level, but so does the damage taken per cast; overall, the amount of damage that needs to be taken per damage effectiveness goes up at higher gem levels. The optimum is a level 2 gem, which requires 1442 damage taken per 100% damage effectiveness. In comparison, a level 20 gem requires 3057 damage taken per 100% damage effectiveness.

Targeting: Targeted spells will cast towards the enemy that caused the last damage. Reflected damage is considered to come from the enemy originally damaged. If the damage was self-caused, it will target a random enemy (if there are no enemies, it will be cast at the player, if it is a projectile, it will be fired in a random direction) ^[3].

Totems: Cast when Damage Taken can't be used with totems.

Gem level progression

Level				Damage Threshold	less/more Damage	maximum Item Level	Exp.	Total Exp.
1	38	40	27	N/A	65% less	38	0	0
2	40	41	29	N/A	63% less	40	388734	388734
3	42	43	30	N/A	61% less	42	477437	866171
4	44	45	31	N/A	59% less	44	583786	1449957
5	46	47	33	N/A	57% less	46	710359	2160316
6	48	49	34	N/A	55% less	48	1355511	3515827
7	50	51	35	N/A	53% less	50	1138877	4654704
8	52	53	37	N/A	51% less	52	1368233	6022937
9	54	55	38	N/A	49% less	54	1638338	7661275
10	56	57	39	N/A	47% less	56	1956648	9617923
11	58	58	41	N/A	45% less	58	3655184	13273107
12	60	60	42	N/A	43% less	60	3017327	16290434
13	62	62	43	N/A	41% less	62	3576232	19866666
14	64	64	44	N/A	39% less	64	4231667	24098333
15	65	65	45	N/A	37% less	65	2395078	26493411
16	66	66	46	N/A	35% less	66	8421063	34914474
17	67	67	46	N/A	33% less	67	16159983	51074457
18	68	68	47	N/A	31% less	68	41170367	92244824
19	69	69	48	N/A	29% less	69	86794448	179039272
20	70	70	48	N/A	27% less	70	157405063	336444335
21	72	72	50	N/A	25% less	72	N/A	N/A
22	74	N/A	N/A	N/A	23% less	74	N/A	N/A
23	76	N/A	N/A	N/A	21% less	76	N/A	N/A
24	78	N/A	N/A	N/A	19% less	78	N/A	N/A
25	80	N/A	N/A	N/A	17% less	80	N/A	N/A
26	82	N/A	N/A	N/A	15% less	82	N/A	N/A
27	84	N/A	N/A	N/A	13% less	84	N/A	N/A
28	86	N/A	N/A	N/A	11% less	86	N/A	N/A
29	88	N/A	N/A	N/A	9% less	88	N/A	N/A
30	90	N/A	N/A	N/A	7% less	90	N/A	N/A
31	91	N/A	N/A	N/A	6% less	91	N/A	N/A
32	92	N/A	N/A	N/A	5% less	92	N/A	N/A
33	93	N/A	N/A	N/A	4% less	93	N/A	N/A
34	94	N/A	N/A	N/A	3% less	94	N/A	N/A
35	95	N/A	N/A	N/A	2% less	95	N/A	N/A
36	96	N/A	N/A	N/A	1% less	96	N/A	N/A
37	97	N/A	N/A	N/A	N/A	97	N/A	N/A
38	98	N/A	N/A	N/A	1% more	98	N/A	N/A
39	99	N/A	N/A	N/A	2% more	99	N/A	N/A
40	100	N/A	N/A	N/A	3% more	100	N/A	N/A

Quest reward

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Vendor reward

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Strategy

Due to the large amount of damage taken needed per damage effectiveness and the rapid scaling of damage taken required per level, it is advisable to use spells for purposes other than damage that do not depend heavily on the active skill level. Possible choices include:

Module Error: Too many skills found with q_where = skill.active_skill_name="Frost Wall". Please choose only one of the following ids:
WbFrostWall - Deals (2-35) to (2-52) Cold Damage, Base duration is (1.60-3.45) seconds, 0.15 seconds between appearance of Wall sections, +(1-2.7) metres to Wall length (page)
ProphecyFrostWall - Deals (2-35) to (2-52) Cold Damage, Base duration is (1.60-3.45) seconds, 0.15 seconds between appearance of Wall sections, +(2-5.4) metres to Wall length (page) to block enemies.
Module Error: No skills found with q_where = skill.active_skill_name="Arctic Breath" to create ground ice.
Passive corpse disposal/minion buffing via Module Error: Too many skills found with q_where = skill.active_skill_name="Detonate Dead". Please choose only one of the following ids:
DetonateDeadRoyale - Deals (10-105) to (15-158) Fire Damage, Explosion deals base Fire Damage equal to 6% of the corpse's Maximum Life, +(0-0.2) metres to radius, Base radius is 2.2 metres (page)
DetonateDead - Deals (15-798) to (22-1197) Fire Damage, Explosion deals base Fire Damage equal to (6-7.9)% of the corpse's Maximum Life, Base radius is (2.2-2.6) metres (page), Module Error: Too many skills found with q_where = skill.active_skill_name="Flesh Offering". Please choose only one of the following ids:
FleshOfferingFairgravesMapBoss - Base duration is 20.00 seconds, Additional 4.00 seconds Base Duration per extra corpse Consumed, Grants Minions 100% increased Attack Speed, Grants Minions 100% increased Cast Speed, Grants Minions 100% increased Movement Speed (page)
BlightNecromancerChampionFleshOffering - Base duration is 3.00 seconds, Additional 1.00 seconds Base Duration per extra corpse Consumed, Grants Minions 25% increased Attack Speed, Grants Minions 25% increased Cast Speed, Grants Minions 25% increased Movement Speed (page), or Bone Offering.
Module Error: Too many skills found with q_where = skill.active_skill_name="Lightning Warp". Please choose only one of the following ids:
LightningWarpHardMode - Deals (1-51) to (19-965) Lightning Damage, +(0-0.4) metres to radius, (0-19)% reduced Duration, Can queue up to 50 uses (page)
LightningWarp - Deals (1-51) to (19-965) Lightning Damage, +(0-0.4) metres to radius, (30-49)% reduced Duration, Can queue up to 50 uses (page) to escape melee range. (Could backfire.)
Curses. This can be a reliable way of automatically casting curses, at the cost of lower curse level.

Some supports also potentially combine well, especially with a persistent rapid-firing skill such as Module Error: Too many skills found with q_where = skill.active_skill_name="Ball Lightning". Please choose only one of the following ids:
ExileBallLightningTrap - Deals (1-110) to (2-204) Lightning Damage, When your Traps Trigger, your nearby Traps also Trigger, Trap lasts +6 seconds, Traps are thrown randomly around targeted location, 200% reduced Projectile Speed, Throw up to (6-10) additional Traps, Base radius is 1.8 metres (page)
StrMissionBallLightning - Deals (1-166) to (2-309) Lightning Damage, Totem lasts 8 seconds, Summons a Totem which uses this Skill, 50% increased Cast Speed, Base radius is 1.8 metres (page):

Module Error: No skills found with q_where = skill.active_skill_name="Blind"
Module Error: No skills found with q_where = skill.active_skill_name="Chance to Flee"
Passive IIR culling via Module Error: No skills found with q_where = skill.active_skill_name="Culling Strike", Module Error: No skills found with q_where = skill.active_skill_name="Item Rarity", and a skill that causes many hits.
Module Error: No skills found with q_where = skill.active_skill_name="Curse On Hit" (As of Version 1.2.2 CWDT will only trigger Ball Lightning in this example, but Ball Lightning will then not trigger Curse On Hit.)
Module Error: No skills found with q_where = skill.active_skill_name="Knockback"
Module Error: No skills found with q_where = skill.active_skill_name="Power Charge On Critical"

Quick reference chart of commonly used spell gems and their maximum allowed level to be supported by each level of CWDT:

Level	Damage Threshold	Damage Modifier	Max level of spell gems	Module Error: Too many skills found with q_where = skill.active_skill_name="Immortal Call". Please choose only one of the following ids: ExileImmortalCall - Base duration is (2.80-5.00) seconds (page) WbImmortalCall - Base duration is (2.80-5.00) seconds (page) (Endurance charge bonus)	Module Error: Too many skills found with q_where = skill.active_skill_name="Molten Shell". Please choose only one of the following ids: GravicusMoltenShell - Base duration is 10.00 seconds, Deals (143-2698) to (214-4048) Fire Damage, Shields break after (752-4460) total Damage is prevented, (4352-19367) additional Armour (page) GoatmanMoltenShellInvasion - Base duration is 10.00 seconds, Deals (15-5246) to (23-7869) Fire Damage, Shields break after (4-2648) total Damage is prevented, (162-4334) additional Armour (page) (additional armour)	Module Error: No skills found with q_where = skill.active_skill_name="Arctic Breath"	Enfeeble	Module Error: Too many skills found with q_where = skill.active_skill_name="Frost Wall". Please choose only one of the following ids: WbFrostWall - Deals (2-35) to (2-52) Cold Damage, Base duration is (1.60-3.45) seconds, 0.15 seconds between appearance of Wall sections, +(1-2.7) metres to Wall length (page) ProphecyFrostWall - Deals (2-35) to (2-52) Cold Damage, Base duration is (1.60-3.45) seconds, 0.15 seconds between appearance of Wall sections, +(2-5.4) metres to Wall length (page)	Tempest Shield	Module Error: Too many skills found with q_where = skill.active_skill_name="Vortex". Please choose only one of the following ids: WaterElementalVortexOnDeath - Deals (14-833) to (21-1250) Cold Damage, Base duration is 7.00 seconds, Deals (6.1-1447) Base Cold Damage per second, Modifiers to Spell Damage apply to this Skill's Damage Over Time effect, 100% chance to Trigger this Spell on Death, Base radius is 2 metres, Base secondary radius is 2 metres (page) FrostBoltNovaRoyale - Deals (3-51) to (5-76) Cold Damage, Base duration is 2.00 seconds, Deals (14.8-228.6) Base Cold Damage per second, Modifiers to Spell Damage apply to this Skill's Damage Over Time effect, 20% less Area of Effect when Cast on Frostbolt, Base radius is 2 metres, Base secondary radius is 2 metres, (0-36)% increased Cooldown Recovery Rate, Can explode from up to 5 Frostbolt Projectiles (page)	Blood Rage	Phase Run	Temporal Chains	Golem (any)
1	528	-70%	38	3 (106%)	10 (156)	4	5	10	7	4	7	3	5	3
2	583	-66%	40	4 (109%)	11 (196)	5	6	11	8	5	8	4	6	4
3	661	-62%	42	5 (112%)	11 (196)	6	7	11	8	6	8	5	7	5
4	725	-58%	44	6 (115%)	12 (245)	7	7	12	9	7	9	6	7	6
5	812	-54%	46	7 (118%)	12 (245)	8	8	12	10	8	10	7	8	7
6	897	-50%	48	8 (121%)	13 (304)	9	9	13	10	9	10	8	9	8
7	1003	-46%	50	9 (124%)	13 (304)	10	10	13	11	10	11	9	10	9
8	1107	-42%	52	10 (127%)	14 (376)	11	11	14	12	11	12	10	11	10
9	1221	-38%	54	11 (130%)	14 (376)	12	12	14	12	12	12	11	12	11
10	1354	-34%	56	12 (133%)	15 (440)	13	13	15	13	13	13	12	13	12
11	1485	-30%	58	13 (136%)	16 (515)	14	14	16	14	14	14	13	14	13
12	1635	-26%	60	14 (139%)	16 (515)	15	15	16	15	15	15	14	15	14
13	1804	-22%	62	15 (142%)	17 (600)	16	16	17	16	16	16	15	16	15
14	1980	-18%	64	16 (145%)	18 (698)	17	17	18	17	17	17	16	17	16
15	2184	-14%	65	16 (145%)	18 (698)	17	17	18	17	17	17	16	17	16
16	2394	-10%	66	17 (148%)	18 (698)	18	18	18	18	18	18	17	18	17
17	2621	-6%	67	17 (148%)	19 (812)	18	18	19	18	18	18	17	18	17
18	2874	-2%	68	18 (151%)	19 (812)	19	19	19	19	19	19	18	19	18
19	3142	+2%	69	19 (154%)	19 (812)	19	19	19	19	19	19	19	19	19
20	3272	+6%	70	20 (157%)	20 (943)	20	20	20	20	20	20	20	20	20
21	3580	+10%	72	21 (160%)	21 (1040)	21	21	21	21	21	21	21	21	21
22	3950	+14%	74	22 (163%)	22 (1148)	22	22	22	22	22	22	22	22	22
23	4350	+18%	76	23 (166%)	23 (1265)	23	23	23	23	23	23	23	23	23

Cats when Damage Taken

Cats when Damage Taken was a trigger gem available only on April 1st 2015. It was a bug caused by a typo in source code.^[4] Like Cast when Damage Taken, it caused a linked spell to activate when the player accumulated damage taken, but besides casting the spell, it also summoned black cats. Other properties were identical to the Cast when Damage Taken skill.

Version history

Version	Changes
2.0.0	Enduring Cry is now a Warcry instead of a spell, therefore it can't be cast anymore.
1.3.1g	Fixed a bug with the trigger gems that cause spells to automatically cats on various conditions.
1.3.1	Spells triggered by Cast on Damage Taken have had their damage reduced by 25%.
1.3.0	Trigger gems are now classified as Trigger.
1.2.2	Gems may now only be supported by a single trigger gem, gems supported by multiple trigger gems will be disabled.
1.0.1	The level requirement of gems augmented by Cast on Damage Taken may not exceed the level requirement of the Cast on Damage Taken gem.
1.0.0f	Cooldown of 250ms added.
1.0.0	Cast when Damage Taken has been added to the game.

References

↑ Mark_GGG (9 October 2013). "Path of Exile Forum". Retrieved 2 July 2015.
↑ Mark_GGG (May 20, 2014). "Path of Exile Forum".
↑ Some experimentation with Heartbound Loop
↑ Chris (April 1, 2015). "Incident Report for April 1 Catastrophe". Retrieved April 1, 2015.

[1] Mark_GGG (9 October 2013). "Path of Exile Forum". Retrieved 2 July 2015.

[2] Mark_GGG (May 20, 2014). "Path of Exile Forum".

[3] Some experimentation with Heartbound Loop

[4] Chris (April 1, 2015). "Incident Report for April 1 Catastrophe". Retrieved April 1, 2015.

[1]

[2]

[3]

[4]

v t e Skills

Skills	Skill gem Transfigured skill gem Vaal skill Cost Reservation

Support	Support gem Awakened support gem Exceptional gem Socket Link

Gem tags	AoE Arcane Attack Aura Blessing Blink Bow Brand Chaining Channelling Chaos Cold Critical Curse Duration Fire Golem Guard Herald Hex Lightning Link Mark Melee Mine Minion Movement Nova Orb Prismatic Projectile Physical Slam Spell Stance Strike Totem Trap Travel Trigger Vaal Warcry

Lists	List of skill gems List of transfigured skill gems List of Vaal skill gems List of support gems List of awakened support gems