Amethyst Golem (Tank 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 (4/Day). If the golem fails a saving throw, it can choose to succeed instead.

Multiattack. The golem makes four slam attacks.

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

Breath Weapon (Recharge 5–6). The golem exhales crushing force in a 60-foot cone. Each creature in that area must make a DC 22 Dexterity saving throw. On a failed save, the creature takes 71 (11d12) force damage and is knocked prone. On a successful save, it takes half as much damage and isn’t knocked prone. On a success or failure, the creature’s speed becomes 0 until the end of its next turn.

Spellcasting (Psionics). The golem casts one of the following spells, requiring no spell components and using Intelligence as the spellcasting ability (spell save DC 22, +14 to hit with spell attack):

1/day each: dispel magic, forcecage, plane shift, reverse gravity, time stop

Change Size. The golem magically transforms into either its True Form or its smallest 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 80 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.

Psychic Beam (Costs 3 Actions). The golem emits a beam of psychic energy in a 90-foot line that is 10 feet wide. Each creature in that area must make a DC 24 Intelligence saving throw, taking 27 (5d10) psychic damage on a failed save, or half as much damage on a successful one.