Freeze. When the ice golem is subjected to cold damage, it instead takes 0 damage, and gains temporary hit points equal to half the damage it would have taken, rounded down. Melt. If the ice golem takes an accumulated 100 fire damage between short or long rests, it transforms into a water elemental with half its maximum hit points, and regains its normal form after finishing a long rest.
Multiattack. The ice golem makes two slam attacks. Cold Breath (Recharge 5–6). The ice golem exhales an icy blast in a 30-foot cone. Each creature in that area must make a DC 15 Constitution saving throw, taking 36 (8d8) cold damage on a failed save, or half as much damage on a successful one. Slam. Melee Weapon Attack: +8 to hit, reach 10 ft., one target. Hit: 14 (2d8 + 5) bludgeoning damage.