Chimera Flesh Golem

Berserk. Whenever the golem starts its turn with 50 hit points or fewer, roll a d6. On a 6, the golem goes berserk. On each of its turns while berserk, the golem attacks the nearest creature it can see, the golem has advantage on this attack roll, but attack rolls against the golem have advantage while it is going berserk. If no creature is near enough to move to and attack, the golem attacks any object of medium size or smaller. Once the golem goes berserk, it continues to do so until it is destroyed or regains all its hit points.

The golem's creator, if within 60 feet of the berserk golem, can try to calm it by speaking firmly and persuasively. The golem must be able to hear its creator, who must take an action to make a DC 15 Charisma (Persuasion) check. If the check succeeds, the golem ceases being berserk. If it takes damage while still at 50 hit points or fewer, the golem might go berserk again.

Immutable Form. The golem is immune to any spell or effect that would alter its form.

Lightning Absorption. Whenever the golem is subjected to lightning damage, it takes no damage and instead regains a number of hit points equal to the lightning damage dealt.

Magic Resistance. The golem has advantage on saving throws against spells and other magical effects.

Multiple Heads. The golem has advantage on Wisdom (Perception) checks and on saving throws against being blinded, charmed, deafened, frightened, stunned, and knocked unconscious.

Magic Weapons. The golem's weapon attacks are magical.

Multiattack. The golem makes three attacks: one with its bite, one with its horns, and one with its claws. When its fire breath is available, it can use the breath in place of its bite or horns.

Bite. Melee Weapon Attack: +10 to hit, reach 5 ft., one target. Hit: 13 (2d6 + 6) piercing damage.

Horns. Melee Weapon Attack: +10 to hit, reach 5 ft., one target. Hit: 12 (1d12 + 6) bludgeoning damage.

Claws. Melee Weapon Attack: +10 to hit, reach 5 ft., one target. Hit: 13 (2d6 + 6) slashing damage.

Fire Breath (Recharge 5–6). The dragon head exhales fire in a 15-­-foot cone. Each creature in that area must make a DC 17 Dexterity saving throw, taking 42 (12d6) fire damage on a failed save, or half as much damage on a successful one.