You may go into a frenzy as a free action. While frenzied, you get a bonus action each Phase but all you may do is move, grapple, melee attack or calm.

You remain frenzied until you are stunned or unconscious or spend an action calming yourself. You may not calm yourself during a Phase in which you attack, complete an attack on overwatch from a previous Phase, or go on overwatch to attack.

If you are stunned or knocked unconscious, you are calmed automatically.