Viper Strike

The thieves guilds of Oriath teach a wicked skill to all initiates - the feared Viper Strike. Employing the skill, a claw, dagger or sword user coats their weapon with deadly venom, a concoction so virulent it permanently marks any weapon it contacts. Once the toxin is applied, the weapon will poison any it strikes, burning deep into their veins, causing wracking, crippling pain. Additional hits will increase the concentration of the toxin, stacking it up to lethal levels quickly. Few have survived an assault of Viper Strike and those who have never forget the agony.

Skill Functions and Interactions

A Viper Strike attack does increased physical damage, and then also has a 50% chance per hit of adding a 'debuff' (a degen charge) which does DoT damage equal to 25% of the initial hit (all damage before any chaos bonuses or DoTs are applied). There is no upper limit to the number of debuffs which may be stacked; it is simply a function of attack speed and debuff duration (7 seconds base).

Viper Strike's initial hit is best scaled as physical damage (although elemental scaling is possible as well), with additional modifications from bonuses to chaos and DoT damage.

Gem level progression

Template:GemLevelTable |- ! 1 | 1 || class="table-na" style="text-align: center; " | N/A || 5 || 0% || 70 |- ! 2 | 2 || class="table-na" style="text-align: center; " | N/A || 5 || 4% || 308 |- ! 3 | 4 || 16 || 5 || 8% || 2,560 |- ! 4 | 8 || 25 || 5 || 12% || 8,813 |- ! 5 | 12 || 33 || 5 || 16% || 22,895 |- ! 6 | 16 || 41 || 6 || 20% || 68,427 |- ! 7 | 21 || 52 || 6 || 24% || 150,439 |- ! 8 | 26 || 62 || 6 || 28% || 581,328 |- ! 9 | 32 || 75 || 6 || 32% || 566,989 |- ! 10 | 38 || 88 || 6 || 36% || 1,143,783 |- ! 11 | 42 || 96 || 7 || 40% || 1,426,490 |- ! 12 | 46 || 104 || 7 || 44% || 2,737,323 |- ! 13 | 49 || 111 || 7 || 48% || 3,289,072 |- ! 14 | 52 || 117 || 7 || 52% || 3,350,845 |- ! 15 | 55 || 123 || 7 || 56% || 9,936,192 |- ! 16 | 58 || 130 || 8 || 60% || 21,346,246 |- ! 17 | 61 || 136 || 8 || 64% || 50,693,883 |- ! 18 | 64 || 142 || 8 || 68% || 90,050,361 |- ! 19 | 66 || 146 || 8 || 72% || 147,034,294 |- ! 20 | 68 || 151 || 8 || 76% || class="table-na" style="text-align: center; " | N/A |- ! 21 | 68 || 151 || 9 || 80% || class="table-na" style="text-align: center; " | N/A |- ! 22 | 68 || 151 || 9 || 84% || class="table-na" style="text-align: center; " | N/A |- ! 23 | 68 || 151 || 9 || 88% || class="table-na" style="text-align: center; " | N/A |- ! 24 | 68 || 151 || || || class="table-na" style="text-align: center; " | N/A |- ! 25 | 68 || 151 || || || class="table-na" style="text-align: center; " | N/A |- ! 26 | 68 || 151 || || || class="table-na" style="text-align: center; " | N/A |}

Damage Formula

Optimizing damage output involves striking a balance between physical damage, chaos and DoT bonuses. The formula which expresses how these different factors relate to overall VS damage is however not simple.

Since each hit has only a 50% chance to apply a DoT charge (GGG refers to this as a 'debuff,' but visually it appears more like a charge of poison), any consideration of the total damage output needs to take this into account: not every hit will weigh equally. For simplicities' sake, we will simply calculate as if the DoT did half the damage it does - which, on average, is the same as having a 50% chance to apply:

Total Damage = (VS Hit) + 0.5 * (VS DoT)

We'll get better insight into how the total damage depends on physical damage, chaos bonuses, and DoT bonuses if we can express these two basic components of VS damage, (VS Hit) and (VS DoT), in terms of those other factors.

VS Hit

The simplest of the two components of total VS damage is the VS Hit, or the initial strike. The Viper Strike gem increases the physical damage of the basic attack, and then also applies an additional 10% of this hit as chaos damage. This chaos damage is further modified by any chaos damage bonuses the character may have.

First of all, we need to calculate the physical damage without any global "increased" modifiers. We start with the Weapon Damage (including all physical modifiers found on the weapon - meaning whatever the weapon tooltip shows), and apply any global additional physical damage:

Min = Weapon Min Damage + Added Min Damage

Max = Weapon Max Damage + Added Max Damage

The average will suffice for our calculations:

Base Damage = (Min + Max)/2

Now we split off 10% of the weapon damage for the extra Chaos damage, and apply all "increased" and/or "reduced" damage modifiers accordingly:

Hit Damage = Base Damage * (1 + sum(increased Physical/Melee/Attack Damage)) + Base Damage * 0.10 * (1 + sum(increased Physical/Melee/Attack Damage) + sum(increased Chaos Damage))

Next, we apply our Critical Strike chance and Multiplier:

Total Critical Strike Chance = Weapon Critical Strike chance * (1+ sum(increased Critical Strike Chance))

Total Critical Strike Multiplier = 1,5 * (1 + sum(increased Critical Strike Multiplier)))

Total Hit Damage = Hit Damage * (Total Critical Strike Chance * (Total Critical Strike Multiplier - 1.0) + 1.0)

Note: I only cover the most basic version of this calculation here. I did not include any added Elemental or Chaos damage, nor any "more/less Damage" modifiers. Since "more/less physical damage" is a common occurrence, to add those you simply calculate the Hit Damage as mentioned above, then multiply it by (1 + more/- less) for each of those modifiers.

Now that we have the Total Hit Damage, the DPS shown in the skill tooltip (which only considers the initial hit) can be calculated simply by multiplying it with your total APS as well as your Chance to Hit (which is quite complicated to calculate - simply check your character screen):

Total APS = Weapon APS * (1 + sum(increased Attack Speed))

Tooltip DPS = Total Hit Damage * Total APS * Chance to Hit

VS DoT

Each tick of each charge does chaos damage of 25% of the initial hit per second, which is then further modified by bonuses to chaos and DoT damage as follows:

Damage per Second = 0.25 * Total Hit Damage * (1 + sum(increased Chaos Damage) + sum(increased Damage over Time))

Total DoT Damage = Damage per Second * 7 * (1 + sum(increased Duration))

This is, assuming the DoT stays on for the full duration.

Total Damage in terms of Physical, Chaos, DoT

Putting these two results back together again, on average, we have:

Total Damage = Total Hit Damage + 0.5 * Total DoT Damage

Therefore, the total DPS concludes to:

Total DPS = Total Damage * Chance to Hit * Total APS

Working out the numbers for other situations is left as an exercise for the reader.

Duration and Attack Speed

In the formula above, you can see that duration is also a factor for total damage. The default duration is 7 seconds, but this can be increased with either support gems or skill duration passives. More than 7 seconds to kill a mob is however already very slow, most mobs should die much faster than that, and so it's probably only in boss fights where the extra duration would be a significant benefit. Situational use of an increased duration support gem in those cases would probably be a more efficient tactic than passive node investment.

A complementary benefit can come from attack speed, especially now (starting in 1.2) that there is no longer an upper limit on the number of degen charges that can be stacked, and yet each hit has only a 50% chance of stacking a charge. Many hits delivered quickly should allow you to then run around out of reach while watching a boss' health drain away.

Vulnerability Curse

Vulnerability is an especially good curse to use with Viper Strike. It has an immediate effect on the initial hit, which directly increases the DoT ticks that follow. Above and beyond that, vulnerability introduces extra bonuses for DoT damage, and so the curse has a kind of double-dip effect for boosting total VS damage.

Quest reward

This skill is the very first gem found by a Shadow on the Twilight Strand beach.

It can also be found as later quest rewards:

• Mercy Mission in Act 1 (Normal), by Shadow
• Breaking Some Eggs in Act 1 (Normal), by Shadow, Ranger and Duelist
• The Caged Brute in Act 1 (Normal), by Ranger

Version history

Version	Changes
1.2.0	This skill now adds 10% of physical damage as Chaos Damage and has a 50% chance to deal 175% of the attack's damage as chaos damage over seven seconds. The effect duration won't be refreshed by new attacks, but there is no limit to how many Viper Strike debuffs an enemy can have.
1.0.3	Damage progression has been increased. It is now around 15% better at level 15 than it was in 1.0.2.
1.0.2b	Fixed a bug where area damage bonuses would not benefit Viper Strike when supported by .
1.0.2	Generic modifiers to damage dealt will now apply to damage over time that your character causes. Damage over time is not spell damage, nor attack damage, so modifiers specific to those types will not apply. Non-specific "increased damage" modifiers will apply to damage over time. Type-specific modifiers will apply as well. For example, "increased fire damage" modifiers will apply to fire damage over time. Viper Strike can be supported by , now that the damage penalty also applies.
0.9.13	Viper Strike is now 38% better at level 1 and 3% better at level 15.
0.9.12qq	From 0.35% attack speed per quality point to 0.5%.
0.9.12d	Fixed a server crash that could occur with Viper Strike.
0.9.5	Fixed Viper Strike so that damage from the degeneration is scaled properly for PvP.
0.9.4	Increased the damage.
0.9.2	Viper Strike does more damage at higher levels than before. Reduced maximum number of charges to 4.
0.9.1	Reduced Viper Strike duration at lower levels.