Wounds the target causing them to bleed for X damage plus an additional [1 * ((MWB + mwb) / 2 + AP / 14 * MWS)] (based on weapon damage) over 15 sec. {If used while your target is above 75% health, Rend does 35% more damage.}
Wounds the target causing them to bleed for X damage plus an additional [1 * ((MWB + mwb) / 2 + AP / 14 * MWS)] (based on weapon damage) over 15 sec. {If used while your target is above 75% health, Rend does 35% more damage.}
"I gave him a choice: die piece by piece, or all at once." — Gorebelly[1]
Rend is a damage over time ability. It is an instant cast, so it doesn't replace a normal attack. It is also one of the few warrior attacks that isn't mitigated by enemy armor. It is available only in Battle and Defensive Stances.
Even without investing in talents to improve it, Rend is a very rage-efficient attack. Investments in Improved Rend and Blood Frenzy makes it shine even brighter. Its disadvantages are partly that it loses efficiency if the target dies before the Rend has completed it's duration. Also, Rend can not be used in Berserker Stance.
In addition to the base damage, Rend will deliver extra damage depending on how hard the weapon hits. The formula looks a bit complicated, but it basically calculates the average weapon damage modified for attack power and takes a fraction of this:
Weapon Speed x Attack Power 743
Extra damage = ( --------------------------- + Average Weapon Damage ) x Duration x ------
14 300000
Note, The DPS of the weapon isn't the most important factor. It's much more important that the weapon is slow.
Example: Wally the warrior has an attack power of 1400, and he uses a Rend with a duration of 21 seconds. When he uses The Unstoppable Force (Speed 3.8, average damage 233½) his rends will do 32 points additional damage. When he uses Widow's Remorse (Speed 1.6, average damage 100½) his rends will only do 13 points of additional damage, even though Widow's Remorse has a slightly higher DPS-rating than the Unstoppable Force.
Tips and Tactics
This is also a good skill to use in PvP against Rogues, as it makes it more difficult (but not impossible) for them to use Vanish and an additional opener such as Cheap Shot or Ambush.
Related talents and glyphs
Improved Rend (Rank 1 arms talent) - increases bleed damage done by 10/20%
Patch 3.0.3 (04-Nov-2008): Damage has been adjusted to be less base and more weapon based. Ranks 9 and 10 now do 35% more damage when the target is above 75% health instead of 4 times damage when the target is enraged.
Patch 1.1.0 (07-Nov-2004): Now available in Battle and Defensive Stance, damage slightly increased on some ranks.
Patch 0.7 (2004-06-15): Damage reduced. Changed to an instant ability.