Berserk Exhaustion

Any exhaustion caused by Berserker's abilities is removed after 1 hour or after killing a creature of CR 3 or higher. When performing any rest type after 30 minutes, remove 1 exhaustion caused by berserker abilities.

Exhaustion caused by the berserker's abilities cannot kill you, but natural exhaustion can still kill you. At LV20, killing removes 1 exhaustion for every creature you kill, and every 10 CR removes 1 additional exhaustion whether caused by the berserker or not.