Ailments

The Basics

Ailments are a special category of effect applied by particular types of damage. Not all debuffs are ailments - if something isn't one of the effects below, it's not an Ailment, and won't scale with Ailment-related effects.

The six Ailments are Freeze, Chill, Shock, Ignite, Poison, and Bleed.

Of these, the first four (Freeze, Chill, Shock, and Ignite) are further classed as Elemental Ailments; Poison and Bleed are not Elemental Ailments. This obeys the usual rule that Elemental means Cold, Lightning, and Fire.

"Damaging Ailments" refers to Ignite, Poison, and Bleed, "non-Damaging Ailments" refers to Freeze, Chill, and Shock.

Technically, there are also three additional Ailments that come only from a few endgame items, called Scorch, Brittle, and Sap, but we won't cover those here since they're only found on particular items. They're both Elemental and Non-Damaging Ailments, mechanically speaking.

Ailment mechanics are somewhat complex, and it's important to understand exactly how they work before building around them. A good mastery of PoE's language and its exact-words phrasing style are both needed to really grasp Ailments properly. This page is as precise as I can be without being wildly over-technical: if it seems complex and wordy, well, any shorter page wouldn't properly cover the mechanics.

Ailments vs. Skills vs. Debuffs

Ailments are not considered Skill Effects (they're a result of the damage of the applying skill, not the skill itself), and do not scale with Skill Effect Duration modifiers. They do, however, benefit from Support gems linked to the applying skill, provided the effects of those Support gems benefit the Ailment (and not just the applying Hit).

The key difference between Ailments and most other debuffs is that Ailments' effects and/or durations scale with the amount of particular types of damage dealt by a skill's Hit. For example, an Ignite applied by a skill that did a lot of Fire damage will do more damage than an Ignite applied by one that did very little Fire damage. However, even if another debuff does scale with damage done, it is still not an Ailment if it is not one of the effects listed here.

The Damaging Ailments

The Damaging Ailments - Ignite, Poison, and Bleed - deal Damage over Time based on the base damage of the Hit that applied them.

Damaging Ailments are not directly affected by modifiers ("Increased" or "More") to their applying skill's damage, with the exception of Added Damage effects. Roughly speaking, the base+added damage of the skill gets split into two parts: one that scales with the skill's tags to compute the damage of the Hit, and the other that scales with any modifiers relevant to the Ailment to compute the damage (or other effects) of the Ailment.

For example, an Attack that deals Chaos damage may apply Poison, and the damage of the Poison depends on the attack's base damage. Increased Attack Damage would affect the Hit, but would not affect the Poison (which depends on the base damage of the Attack, and does not itself scale with Attack damage modifiers). Increased Poison Damage would affect the Poison, but not the Hit (because the Hit does not deal Poison Damage). Increased Chaos Damage, however, would affect both the Hit (which deals Chaos damage) and the Poison (which also deals Chaos damage).

To further confuse matters, most Passive nodes that grant Attack damage also grant damage with Ailments from Attacks - but these are still separate effects, and the one does not imply the other.

In addition to the modifiers listed for each Ailment below, they're also affected by Mine, Totem, Minion, or Trap damage if the Ailment was applied by Mine, Totem, Minion, or Trap damage.

Most builds that use Damaging Ailments work in one of two ways. Either they scale Ailments to the exclusion of their applying Hits, relying on Ailments to do most of their damage, or they try to scale both using a stat shared by both the Hit and the Ailment (this works particularly well with Ignite, since Fire damage is easier to scale).

Ignite

Applying Ignite: Ignite is applied by Hitting with Fire damage that has a Chance to Ignite. All Critical Strikes, by default, have 100% Chance to Ignite, and will therefore always Ignite unless somehow prevented from doing so, but non-crits can Ignite if you have any Chance to Ignite bonuses on you or the applying skill.

Ignite Damage: Ignite has a base duration of 4 seconds, and deals 50% of the base damage of the applying Hit per second, for a total of 200% of the base damage of the applying Hit. Increasing its duration will keep the damage level of damage for a longer time, increasing the total damage dealt.

Scaling Ignite: Ignite damage is Fire Damage over Time, and scales with modifiers to generic damage, Ignite damage, Fire or Elemental damage, Damage over Time, Burning damage, and Ailment damage. It does not scale with Spell or Attack damage, since it is not a Spell or Attack even if it was applied by one (it is Damage over Time, which is mutually exclusive with both). Ignite duration can be increased by Ailment or Ignite Duration modifiers. Like all Ailments, Ignite does not scale with Skill Effect Duration.

Ignite Limit: Only one Ignite can deal damage to a target at a time. If more than one Ignite is applied at once, all of their durations will tick down, but only the highest-damage Ignite will deal damage at any given moment.

Ignite vs. Burning: Ignite is an example of, but not the same thing as, Burning. "Burning" simply means Fire Damage over Time, which can be done by effects other than Ignite as well.

Non-Fire Ignites: In cases where Ignite is applied by a damage type other than Fire by some means that overrides the normal restriction to Fire damage, the Ignite still deals Fire damage, but is also affected by modifiers to the damage type that caused it. So, for example, if Cold damage Ignites, the portion of the Ignite caused by Cold damage will scale with modifiers to Cold damage, although it still deals Fire damage. This is similar to the rules for damage conversion listed on the "How Damage Works" page.

Bleed

Applying Bleed: Bleed is applied by Physical damage Hits from Attacks (not Spells or other sources of Physical damage) that have a Chance to Bleed. Chance to Bleed can be acquired as a stat on the Passive Tree or from items. Note that unlike some other ailments, Critical Strikes are not guaranteed to apply Bleed.

Bleed Damage: Bleed has a base duration of 5 seconds, and deals 70% of the base Physical damage of the applying Hit per second, for a total of 350% of the base Physical damage of the applying Hit. Increasing its duration will keep the damage level of damage for a longer time, increasing the total damage dealt. Bleed deals increased damage to moving targets: player-applied Bleed does double damage, and monster-applied bleed does six times damage, to moving targets.

Scaling Bleed: Bleed is Physical Damage over Time, and scales with modifiers to generic damage, Bleed damage, Physical damage, Damage over Time, and Ailment damage. It does not scale with Attack damage, since it is not an Attack even if it was applied by one (it is Damage over Time, which is mutually exclusive with being an Attack). Bleed's duration can be increased by Ailment or Bleed Duration modifiers. Like all Ailments, Bleed does not scale with Skill Effect Duration.

Bleed Limit: Only one Bleed can deal damage to a target at a time. If more than one Bleed is applied at once, all of their durations will tick down, but only the highest-damage Bleed will deal damage at any given moment. This rule can be overriden by the Crimson Dance Keystone Passive (which allows up to 8 Bleeds to tick at a time at the cost of halving their damage and removing the bonus to moving targets) and by many monster Bleed effects (most notably the often-fatal Corrupted Blood, which stacks indefinitely).

Poison

Applying Poison: Poison is applied by Physical and Chaos damage from Hits that have a Chance to Poison. Chance to Poison can be acquired as a stat on the Passive Tree or from items. Note that unlike some other ailments, Critical Strikes are not guaranteed to apply Poison.

Poison Damage: Poison has a base duration of 2 seconds, and deals 20% of the combined Physical and Chaos base damage of the applying Hit per second, for a total of 40% of the combined Physical and Chaos base damage of the applying Hit.

Scaling Poison: Poison is Chaos Damage over Time (even if it was applied by Physical damage, it deals Chaos damage), and scales with modifiers to generic damage, Poison damage, Chaos damage, Damage over Time, and Ailment damage. It does not scale with Spell or Attack damage, since it is not a Spell or Attack even if it was applied by one (it is Damage over Time, which is mutually exclusive with both). Like all Ailments, Poison does not scale with Skill Effect Duration.

Stacking Poison: Unlike Bleeds and Ignites, Poison has no limit on the number of Poisons that can deal damage at a time, although each individual Hit can only apply one Poison. Each Poison stack is applied and ticks separately, and none of them in any way interact with the others; existing stacks do not have their duration refreshed by the application of a new one.

Non-Chaos Poison: In cases where Poison is applied by a damage type other than Chaos (Physical by default, or other types by various special means), it still deals Chaos damage, but is also affected by modifiers to the damage type that caused it. So, for example, if Physical damage inflicts Poison, the portion of the Poison caused by Physical damage will scale with modifiers to Physical damage, although it still deals Chaos damage. Note that this usually only matters in cases of Global Physical Damage: sources of Increased Physical Attack Damage with <Weapon Type> will not apply because the problem is the Damage Source (Poison is not itself an Attack, even if it was applied by one), not the Damage Type. This is similar to the rules for damage conversion listed on the "How Damage Works" page.

The Non-Damaging Ailments

In contrast to the Damaging Ailments above, the non-Damaging Ailments - Chill, Freeze, and Shock - apply powerful status effects based on the size of the applying hit. Unlike Damaging Ailments, they consider the final damage of the Hit, not its base damage, in determining their effect.

The duration of non-Damaging Ailments is based on the size of the Hit's eligible damage as compared to the target's total Life. The larger the hit relative to the health pool, the more effective the Ailment. If the effect of the non-Damaging Ailment doesn't meet a minimum threshold, it can fail to apply the Ailment to a target at all, even if you nominally have 100% chance to apply it.

Shock

Applying Shock: Shock is applied by Hitting with Lightning damage that has a Chance to Shock. All Critical Strikes, by default, have 100% Chance to Shock, and will therefore always attempt to Shock unless somehow prevented from doing so, but non-crits can Shock if you have any Chance to Shock bonuses on you or the applying skill. Some other effects can apply Shock in unique ways without dealing damage.

Shock's Effect: Shock has a base duration of 2 seconds, and increases all damage (not just Lightning damage) done to the target by an amount that depends on the amount of total Lightning damage dealt by the applying Hit. The damage increase is 1% per 0.2% of the target's maximum life dealt by the applying Lightning damage, up to a maximum of 50% increased damage taken. If the Shock would increase damage taken by less than 1%, it will fail to apply. If the Shock is applied by a non-damaging means, it will increase damage taken by 20%.

Scaling Shock: Modifiers to Effect of non-Damaging Ailments or Effect of Shock will increase the effect of Shock's damage-taken increase, and modifiers to Ailment or Shock Duration will increase its duration. Like all Ailments, Shock does not scale with Skill Effect Duration. Note that Increased Effect of Shock modifiers do not raise the 50% cap; they just make it easier to reach.

Shock Limit: Only one Shock can apply to a target at a time. Shock is applied after the applying Hit deals damage, and does not increase that Hit's damage.

Technical Note: Note that although Shock's damage-taken is worded as "Increased", it is stronger than 'Increased' wording would suggest because it's an increase to your target's damage taken (not to your damage done). Shock's effect on damage takes place after all of your own modifiers have applied, and is not added to Increased modifiers to your damage done, meaning that it has a more-or-less multiplicative effect on damage. It is additive only with other damage-taken effects on the target, of which there often are very few.

Freeze

Applying Freeze: Freeze is applied by Hitting with Cold damage that has a Chance to Freeze. All Critical Strikes, by default, have 100% Chance to Freeze, and will therefore always attempt to Freeze unless somehow prevented from doing so, but non-crits can Freeze if you have any Chance to Freeze bonuses on you or the applying skill.

Freeze's Effect: Freeze Slows the affected target by 100%. This is animation speed, not just movement speed, and therefore prevents the target from doing anything unless they have bonus speed effects to counteract it. Some high-end bosses have a minimum action speed and so, while not entirely immunee to Freeze, are less affected by it. The duration of Freeze is based on the Cold damage of the applying Hit, with a base duration of 0.06 seconds per 1% of the target's maximum life dealt in Cold damage. If the Freeze would last less than 0.3 seconds (after duration modifiers), it will fail to apply.

Scaling Freeze: Freeze benefits from bonuses to Ailment or Freeze Duration. I would speculate that it also benefits from modifiers to Effect of non-Damaging Ailments, but this would so rarely matter (because Freeze already slows by 100%) that it can be effectively ignored. Like all Ailments, Freeze does not scale with Skill Effect Duration.

Shattering: Killing a Frozen enemy shatters them into pieces, preventing most on-death effects from occurring. In particular, it prevents them from leaving a corpse, which stops enemies (or you) from making use of said corpse.

Implies Chill: Freezing an enemy also Chills them (see below) for the duration of the Freeze plus another 0.3 seconds. As a result, they count as Chilled while Frozen, which can be relevant for some modifiers.

Chill

Applying Chill: Chill is applied by any Hit of Cold damage by default. It does not require a Critical Strike or "Chance to Chill" (which does not exist), and any Cold damage Hit will attempt to Chill unless somehow prevented from doing so (though small hits may fail to hit the minimum threshold described below). Some other effects can apply Chill in unique ways without dealing damage.

Chill's Effect: Chill has a base duration of 2 seconds, and slows the animation (not just movement) speed of the affected target. Chill slows the target by 1% for each 0.33% of the target's life done in Cold damage by the applying Hit, up to a maximum of 30%. If a Chill would slow by less than 1%, it will fail to apply. If the Chill is applied by a non-damaging source, it will slow by 10%.

Scaling Chill: Modifiers to Effect of non-Damaging Ailments or Effect of Chill will increase the effect of Chill's slow, and modifiers to Ailment or Chill Duration will increase its duration. Like all Ailments, Chill does not scale with Skill Effect Duration. Note that Increased Effect of Chill modifiers do not change the 30% cap; they only make it easier to reach.