Brain Golem

Siege Monster. Attacks do double damage to structures and buildings.

Impenetrable Mind. The Brain Golem is immune to attacks that would affect it mentally or psychologically. Only its controller can speak with it telepathically.

Neuron Splitter. When the Brain Golem is deactivated by its controller, it splits into two separate smaller Brain Golems (half all of it's HP, Attack Rolls, Damage Rolls, and its AC is 9).

Multiaction. The Brain Golem gets 3 actions every turn.

Slam. Melee Weapon Attack: +15 to hit, reach 20 ft., 1 target. Hit: (6d12 + 7) [bludgeoning] damage. 

Charge. Melee Weapon Attack: +15 to hit, reach 5-300 ft., all targets in path. Hit: (4d12 + 7) [bludgeoning] damage. 

Brain Ball. Ranged Weapon Attack: +15 to hit, range 5/1000 ft., all targets in a 30 ft sphere. Hit: (9d10 + 5) [psychic] damage.

Jump. The Brain Golem can jump 100 ft up into the air. When it lands, all creatures with in a 30 ft. radius of the landing zone must succeed a DC 15 DEX saving throw or take 3d8 [force] damage.

Psyche Shield. When the Brain Golem is standing still, it can use a reaction to generate a shield around its body, giving it +7 AC until the end of the turn.

Legendary Resistance (Costs 1 Reaction). Using a reaction, the Brain Golem can succeed a saving throw that it would've failed.

Psyche Strike (Charges 6, Costs 1 Action). Using a action, you can target up to 6 creatures. They all must succeed a DC 17 WIS saving throw, or be paralyzed for 1 round.