Arcane Raptor

Elemental Absorption. Whenever the raptor is subjected to fire, cold, or lightning damage, it takes no damage and instead regains a number of hit points equal to the fire, cold, or lightning damage dealt.

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

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

Adamantine Form. The raptor does not take additional damage from critical hits and is immune to rust.

Spellcasting. The raptor is a 20th-level spellcaster, but has no cantrips. Its spellcasting ability is Intelligence. The raptor has the following spells prepared:

1st level (4 slots): Bane, Chromatic Orb, Inflict Wounds, Magic Missile, Sleep

2nd level (3 slots): Blindness/Deafness, Gust of Wind, Scorching Ray, Shatter

3rd level (3 slots): Call Lightning, Fear, Lightning Bolt, Wind Wall

4th level (3 slots): Blight, Control Water, Ice Storm, Wall of Fire

5th level (3 slots): Cone of Cold, Flame Strike, Seeming

6th level (2 slots): Circle of Death, Freezing Sphere

7th level (2 slots): Fire Storm, Teleport

8th level (1 slot): Dominate Monster, Earthquake

9th level (1 slot): Prismatic Wall, Storm of Vengeance

Multiattack. The raptor makes up to three spell attacks whose summed spell slot cost is equal to or less than nine, and may make one other attack.

Antimagic Shockwave. The raptor may, instead of casting any spells on its turn, release a massive shockwave across the weave. All concentration spells, partially completed rituals, and other ongoing or partially casted spells within 960 feet of the raptor are immediately interrupted and ended.

Veritable Gaze. The raptor gazes upon any creature in its blindsight range. That creature must make a DC 20 Constitution saving throw or take 22 (4d10) radiant damage and lose all resistances and immunities for 24 hours.

Thunder. The raptor unleashes a terrifying boom. All creatures within 50 feet of the raptor must make a DC 22 Constitution saving throw or be frightened for 10 minutes.

Retribution. Upon taking damage from a material weapon, the raptor releases a pulse of energy. All creatures within 10 feet of the raptor take 14 (4d6) bludgeoning damage and are pushed back 10 feet.

The raptor can take 3 legendary actions. The raptor regains spent legendary actions at the start of its turn.

Spellcast (Costs 2 Actions). The raptor casts a spell of 4th level or lower.

Adamantine Shard. The raptor launches a portion of its adamantine frame at a target. The raptor takes 5 damage, and the target takes 11 (2d10) magical piercing damage. The raptor may, after combat, retrieve its launched shards and regain 5 hit points for each one.