Mortal Strike is a level 5 Arms warrior ability. It is one of the most powerful and important attacks in the Arms warrior's arsenal, dealing substantial damage, applying a healing debuff.
Mortal Strike is one of Arms warriors' most powerful attacks. Arms warriors should use Mortal Strike whenever possible.
Mortal Strike also applies the [Mortal Wounds]healing debuff. This can be useful in PvP to stop enemy healers from healing a target your group is attempting to focus fire on.
The healing reduction effect does not stack with any other healing reduction effect.
The 4-piece set bonus from the warrior's Tier-8.25 set, Conqueror's Siegebreaker Battlegear (level 80) gives a 10% increased chance to crit with Mortal Strike.
Trivia
Mortal Strike is a rare Warrior spell in Hearthstone. The flavor text reads: ""If you only use one ability, use Mortal Strike." - The Warrior Code, Line 6"
Patch changes
Hotfix (2017-06-14):Mortal Strike damage reduced by 30% in PvP situations.
Patch 5.4.0 (2013-09-10): Now deals 215% of weapon damage (up from 175%).
Hotfix (2012-09-20):Mortal Strike now does 165% weapon damage (down from 185%).
Patch 5.0.4 (2012-08-28): Now generates 10 Rage instead of consuming Rage. Weapon damage increased from 150% to 185%, cooldown increased from 4.5 to 6 sec.
Patch 4.3.0 (2011-11-29): Mortal Strike now reduces the target's healing received by 25%, up from 10%.
Patch 4.0.6 (2011-02-08): Mortal Strike cost has been reduced by 5 rage.