Constructed Guardian

Berserk. Whenever the guard starts its turn with 30 hit points or fewer, roll a d8. On a 7 or 8, the guard goes berserk. On each of its turns while berserk, the guard 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. The Guard regains HP equal to half of which it deals when berserk.

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

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

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

Multiattack. The guard makes two Shortsword attacks.

Shortsword. Melee Weapon Attack: +5 to hit, reach 5 ft., one target. Hit: 13 (2d6 + 6) slashing damage.

Greatsword. Melee Weapon Attack: +5 to hit, reach 5 ft., one target. Hit: 17 (2d10 + 6) slashing damage.

Heavy Crossbow. Ranged Weapon Attack: +3 to hit, reach 5 ft., one target. Hit: 13 (2d10 + 2) piercing damage.