Amethyst Golem (True Form)

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

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

Magic Weapons. The golem's weapon attacks are magical.

Legendary Resistance (3/Day). If the golem fails a saving throw, it can choose to succeed instead.

Multiattack. The golem makes two slam attacks.

Slam. Melee Weapon Attack: +10 to hit, reach 5 ft., one target. Hit: 19 (3d8 + 6) bludgeoning damage.

Singularity Breath (Recharge 5–6). The golem creates a shining bead of gravitational force in its mouth, then releases the energy in a 60-foot cone. Each creature in that area must make a DC 20 Strength saving throw. On a failed save, the creature takes 45 (10d8) force damage, and its speed becomes 0 until the start of the golem’s next turn. On a successful save, the creature takes half as much damage, and its speed isn’t reduced.

Spellcasting (Psionics). The golem casts one of the following spells, requiring no spell components and using Intelligence as the spellcasting ability (spell save DC 18):

1/day each: blink, control water, dispel magic, protection from evil and good, sending

Change Size. The golem magically transforms into either the larger Tank Form or smaller Travel Form, Its statistics change accordingly. This transformation ends if the golem is reduced to 0 hit points or uses a bonus action to end it and go back to its True Form.

Psychic Step. The golem magically teleports to an unoccupied space it can see within 60 feet of it.

The golem can take 3 legendary actions, choosing from the options below. Only one legendary action option can be used at a time and only at the end of another creature’s turn. The golem regains spent legendary actions at the start of its turn.

Slam. The golem makes one slam attack.

Psionics (Costs 2 Actions). The golem uses Psychic Step or Spellcasting.

Explosive Crystal (Costs 3 Actions). The golem spits an amethyst that explodes at a point it can see within 60 feet of it. Each creature within a 20-foot-radius sphere centered on that point must succeed on a DC 20 Dexterity saving throw or take 13 (3d8) force damage and be knocked prone.