Immutable Form. The golem can't shape-shift.
Magic Resistance. The golem has Advantage on saving throws against spells and other magical effects.
Multiattack. The golem makes two attacks, using Slam or Force Bolt in any combination.
Slam. Melee Attack Roll: +10, reach 5 ft. Hit: 15 (2d8+6) Bludgeoning damage plus 9 (2d8) Force damage.
Force Bolt. Ranged Attack Roll: +9, range 90 ft. Hit: 26 (4d12) Force damage.
Slow (Recharge 5–6). The golem casts the Slow spell, requiring no spell components and using Constitution as the spellcasting ability (spell save DC 17).