Fire Absorption. Whenever the golem is subjected to fire damage, it takes no damage and instead regains a number of hit points equal to the fire damage dealt.
Immutable Form. The golem is immune to any spell or effect that would alter its form.
Magic Resistance. The golem has advantage on saving throws against spells and other magical effects.
Magic Weapons. The golem's weapon attacks are magical.
Multiattack. The golem makes two melee attacks.
Slam. Melee Weapon Attack: +13 to hit, reach 5 ft., one target. Hit: 3d8 + 10 bludgeoning damage
Lightning Breath (Recharge 6). The golem exhales shocking spray in a 15-foot cone. Each creature in that area must make a DC 19 Constitution saving throw, taking 45 (10d8) lightning damage on a failed save, or half as much damage on a successful one.
Bosh can take 2 legendary actions, choosing from the options below. Only one legendary action option can be used at a time and only at the end of another creature's turn. Bosh regains spent legendary actions at the start of its turn.
Enraged Retaliate. 1 Action. Upon taking damage, Bosh can use the 'Slam' Action.
Final Stand. 2 Actions, Must below 30 hp. Upon dropping to below 30 hp, Bosh flails out in all directions dealing 5d8 + 10 Bludgeoning Damage and are knocked back 15 feet. Bosh gains an extra 3d8 damage per 'Slam' for the remainder of the fight.