Berserk

Whenever the creature starts its turn with X hit points or fewer, roll a d6. On a 6, the creature goes berserk. On each of its turns while berserk, the creature attacks the nearest creature it can see. If no creature is near enough to move to and attack, the golem attacks an object, with preference for an object smaller than itself. Once the creature goes berserk, it continues to do so until it is destroyed or regains all its hit points. (Clay Golem, pp. 168, MM)