Decimating Strike

Only a Hit made while the enemy is still on Full Life can trigger the effect. Against an enemy with 100,000 single-player Life, Decimating Strike removes between 5,000 and 30,000 Life, then the triggering Hit deals its normal damage. The removal is not part of the Hit, does not replace the Hit, and cannot trigger again after the target has lost Life unless it first returns to Full Life.

The trigger requires a Hit against Full Life

The target must be at 100% of maximum Life when the Hit is evaluated. Damage over time does not Hit and cannot trigger Decimating Strike. Any earlier loss of Life from another player, a Minion, an ailment, or another effect prevents the trigger until the enemy returns to Full Life.

Life is removed before Hit damage

When the condition is met, the game removes a random value between 5% and 30% of the enemy's Life before applying the triggering Hit's damage. The Hit still resolves afterward with its ordinary damage, critical-strike, ailment, stun, and other applicable calculations.

Full-Life bonuses still apply to the triggering Hit

The enemy was on Full Life when the Hit began, so modifiers that apply to Hits against Full Life enemies still apply to that Hit even though Decimating Strike removes Life immediately before its damage is dealt.

The removal is separate from damage

The tooltip says that Life is removed before the damage of the Hit. Do not scale the removed percentage with Attack Damage, Spell Damage, critical damage, damage conversion, penetration, or enemy damage-taken modifiers. Those modifiers can affect the Hit that follows, not the 5% to 30% removal.

Damaged Energy Shield does not by itself mean damaged Life

Full Life is a Life state. An enemy can have damaged Energy Shield while its Life remains full, so the next eligible Hit can still satisfy Decimating Strike if no effect has removed Life.

Party scaling uses the single-player Life basis

The percentage is calculated from the monster's single-player Life rather than its party-scaled Life. A party-scaled monster therefore loses a smaller fraction of the Life shown for that multiplayer encounter.

The percentage is not a fixed 17.5%

Each eligible trigger selects a value somewhere in the stated 5% to 30% range. The public tooltip does not promise the midpoint, a fixed roll, or a particular probability distribution, so practical calculations should use the minimum and maximum rather than assuming 17.5%.

Do not assume same-Hit Culling Strike order

Both Decimating Strike and Culling Strike are described as checks that occur before Hit damage. The current public definitions do not establish which effect resolves first on the same Hit. A later Hit can Cull normally after Decimating Strike and the first Hit have lowered the enemy's Life.