Flesh Golem

If the monster takes Fire damage, it has Disadvantage on attack rolls and ability checks until the end of its next turn.

Whenever the monster starts its turn Bloodied, roll. On a 6, the monster goes berserk. On each of its turns while berserk, the monster attacks the nearest creature it can see. If no creature is near enough to move to and attack, the monster attacks an object. Once the monster goes berserk, it remains so until it is destroyed or it is no longer Bloodied. The monster's creator, if within feet of the berserk monster, can try to calm it by taking an action to make a DC 15 Charisma (Persuasion) check; the golem must be able to hear its creator. If this check succeeds, the golem ceases being berserk until the start of its next turn, at which point it resumes rolling for the Berserk trait again if it is still Bloodied.

The monster can't shape-shift.

Whenever the monster is subjected to Lightning damage, it regains a number of Hit Points equal to the Lightning damage dealt.

The monster has Advantage on saving throws against spells and other magical effects.

The monster makes two Slam attacks.

Melee Attack: +7 to hit. reach 5 ft. Hit: 2d8 + 4 bludgeoning plus 1d8 lightning damage.