Charred One of Friabolt

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

Immutable Form. The charred one is immune to any spell or effect that would alter its form.

Fire Absorption. Whenever the charred one is subjected to fire damage, it takes no damage and instead regains a number of hit points equal to the fire damage dealt.

Magic Resistance. The charred one has advantage on saving throws against spells and other magical effects.

Magic Weapons. The charred one's weapon attacks are magical.

Multiattack. The charred one makes two charred slam attacks.

Charred Slam. Melee Weapon Attack: +7 to hit, reach 5 ft., one target. Hit: 13 (2d8 + 4) bludgeoning damage, plus 4 (1d6) fire damage.