Cadaver Golem

Aversion of Fire. If the golem takes fire damage, it has disadvantage on attack rolls and ability checks until the end of its next turn.

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.

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

Reckless. At the start of its turn, the golem can gain advantage on all melee weapon attack rolls it makes during that turn, but attack rolls against it have advantage until the start of its next turn.

Multiattack. The golem makes two slam attacks.

Slam. Melee Weapon Attack: +8 to hit, reach 5 ft., one target. Hit: 13 (2d8 + 5) bludgeoning damage. The golem lands a critical hit on a roll of 19 or 20.

Assimilate Flesh. Melee Weapon Attack: +8 to hit, reach 5 ft., one creature made of flesh. Hit: 37 (6d10 + 5) necrotic damage. The target’s hit point maximum is reduced by an amount equal to the necrotic damage taken, and the golem regains hit points equal to that amount. The reduction lasts until the target finishes a long rest. The target dies if its hit point maximum is reduced to 0.

Greedy Assimilation. When a creature drops to 0 hit points within 5 feet of the golem, or if the golem lands a critical hit, the golem uses its Assimilate Flesh on the target, hitting automatically.