Rage

From IvaPedia

Rage is a unique ability known only by the most combat hardened; the BattleRager. Using the ebb and flow of battle, no force is as devastating as a BattleRager giving their up will to focus upon their inner rage. Their attacks become wilder, their defenses begin to shrink, and the Rager becomes a combat powerhouse.

In game, there is a large variety of skills a BattleRager has that are 'dependant' upon his/her rage. Some increase one's rage, others completely drain away his/her rage to increase it's effects. The skills are; Bite, Steel Fury, Bleed, Death Wish, Strangle, Knee, Carve, Uppercut, Suppress, Hack, Reckless, Enrage, Whirlwind, Rampage, Savagery.