Brain Golem

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

The golem is considered to be under the effect of a mage armour spell. A dispel magic spell can remove this effect until the golem's next Short Rest.

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

The golem's weapon attacks are magical.

The golem makes two slam attacks.

Melee Weapon Attack: +7 to hit, reach 5 ft., one target. Hit: 15 (2d10 + 4) bludgeoning damage.

The golem magically emits psychic energy in a 60-foot cone. Each creature in that area must succeed on a DC 13 Intelligence saving throw or be stunned for 1 minute. A creature can repeat the saving throw at the end of each of its turns, ending the effect on itself on a success.