Skaab

Whenever the golem starts its turn with 40 hit points or fewer, roll a d6. On a 6, the golem goes berserk. On each of its turns while berserk, the golem attacks the nearest creature it can see. If no creature is near enough to move to and attack, the golem attacks an object, with preference for an object smaller than itself. Once the golem goes berserk, it continues to do so until it is destroyed or regains all its hit points.

The golem's creator, if within 60 feet of the berserk golem, can try to calm it by speaking firmly and persuasively. The golem must be able to hear its creator, who must take an action to make a DC 15 Charisma (Persuasion) check. If the check succeeds, the golem ceases being berserk. If it takes damage while still at 40 hit points or fewer, the golem might go berserk again.

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

The golem is immune to any spell or effect that would alter its form.

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.

The golem has advantage on saving throws against spells and other magical effects.

The golem's weapon attacks are magical.

The most basic skaabs are simply flesh golems, as described in the Monster Manual. But the aspiration of every skaberen is to produce a truly unique masterpiece, a goal that might see a stitcher create golems with one of the following special characteristics.

Increase the skaab's Armor Class to 14 and increase its challenge rating to 6 (2,300 XP).

The skaab's multiattack action allows it to make three slam attacks. Increase its challenge rating to 6 (2,300 XP).

The skaab has advantage on Wisdom (Perception) checks and on saving throws against being blinded, deafened, stunned, and knocked unconscious. (Its challenge rating doesn't change.)

This skaab has three heads, six arms, and armor plating. Increase its challenge rating to 7 (2,900 XP).

The skaab has a flying speed of 30 feet.

The golem makes two slam attacks.

Melee Weapon Attack: +7 to hit, reach 5 ft., one target. Hit: 13 (2d8 + 4) bludgeoning damage.