The Death Rage - also known as Kuruth in the First Tongue- is a state of mind a werewolf will enter when he loses control of his anger. It is a reminder of the death of Father Wolf and a warning of the death that follows in an enraged Uratha's wake. The truest meaning, however, is that succumbing to Kuruth is a loss of self akin to death—and that it courts the possibility of dying like a rabid beast instead of as a warrior or hunter.
When the Death Rage hits, a uratha will automatically assume the Gauru form. While in the grip of Kuruth, a werewolf can't perceive other beings as anything other than moving shapes that his instincts guide him to attack. He attempts to destroy any potential target he can see, friend or foe. Spirits shy away from a werewolf that succumbed to his rage and it is difficult for anyone to coerce with a being lost in the death Rage, even with supernatural means.