Acid Golem

Toxic Absorption. Whenever the golem is subjected to poison or acid damage, it takes no damage and instead regains a number of hit points equal to the 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 or two acid shot attacks.

Slam. Melee Weapon Attack: +13 to hit, reach 5 ft., one target. Hit: 20 (3d8 + 7) bludgeoning damage and 5 (1d10) acid damage.

Acid Shot. Range Weapon Attack: +10 to hit, reach 60 ft., one target. Hit: 27 (3d10 + 7) acid damage.

Acid Stream (Recharge 5-6). The golem exhales acid stream in a 30-foot line that is 5 feet wide. Each creature in that area must make a DC 20 Dexterity saving throw, taking 45 (10d8) acid damage on a failed save, or half as much damage on a successful one.