- If you are looking for the Black Guard's special game mechanic, please see Hatred (Black Guard).
"Aggro" (Aggression), or Threat, which is referred to by Warhammer Online and the player abilities in the game as "Hate" or "Hatred", is a game mechanic which determines who an enemy Non-Player Character will attack at any given time. The player who has built up the greatest amount of "Hatred" with the NPC is the one on whom the NPC will focus its attacks. Many abilities in the game allow a player to control the amount of "Hatred" he generates, to ensure that the enemies focus on the Tank and not on the healers and damagers. Tanks are given abilities to increase the amount they generate, or reduce the amount their companions generate, while damagers are given abilities to reduce the amount they generate, or the amount that the NPC currently has towards them. There are also Tank specific abilities which cause the enemy to temporarily ignore "Hatred" levels and focus on the tank no matter what.
"Aggro" is also sometimes used as a verb, synonymous to Pull, in which case it refers to the initial act of being spotted by an enemy NPC (intentionally or otherwise), causing them to begin attacking you.
When someone attempting to Tank loses the creature they are tanking, that is sometimes referred to as a Peel. As in Dark Age of Camelot, by the same publisher, the number of creatures you pull when attacking a group is said to be determined by the number of members in your party, but the specifics of this system have yet to be clarified.
A Black Orc is swinging away at a huge Giant. A Goblin Shaman and a Goblin Squig Herder come along and see their friend in trouble. The Shaman and Squig Herder join the fight and begin healing the Black Orc and attacking the Giant. Both the Shaman and Squig Herder are generating "Hatred" each time they heal someone involved in the fight, or damage the creature directly. If the Black Orc has trouble hitting the Giant, he may Peel and begin attacking one of his companions, once one of them has generated more "Hatred" than the Black Orc.