Stone Golem

The monster can't shape-shift.

The monster has Advantage on saving throws against spells and other magical effects.

The monster makes two attacks, using Slam or in any combination.

Melee Attack: +10 to hit. reach 5 ft. Hit: 2d8 + 6 bludgeoning plus 2d8 force damage.

Ranged Attack: +10 to hit. range 120 ft. Hit: 4d10 force damage.

The monster casts the Slow spell, requiring no spell components and using Constitution as the spellcasting ability.

You alter time around up to six creatures of your choice in a 40-foot Cube within range. Each target must succeed on a Wisdom saving throw or be affected by this spell for the duration. An affected target's Speed is halved, it takes a −2 penalty to AC and Dexterity saving throws, and it can't take Reactions. On its turns, it can take either an action or a Bonus Action, not both, and it can make only one attack if it takes the Attack action. If it casts a spell with a Somatic component, there is a 25 percent chance the spell fails as a result of the target making the spell's gestures too slowly. An affected target repeats the save at the end of each of its turns, ending the spell on itself on a success. The inline roll above will return 1 if it succeeded or 0 if it failed.