Angrath the Planeswalker

Adamantine Breastplate. While wearing his +2 Adamantine Breastplate, Angrath is immune to critical hits. Any critical hit dealt to Angrath is considered normal damage. 

Charge. If the minotaur moves at least 10 feet straight toward a target and then hits it with a gore attack on the same turn, the target takes an extra 9 (4d8) piercing damage. If the target is a creature, it must succeed on a DC 17 Strength saving throw or be pushed up to 10 feet away and knocked prone. 

Labyrinthine Recall. The minotaur can perfectly recall any path it has traveled.

Reckless. At the start of its turn, the minotaur can gain advantage on all melee weapon attack rolls it makes during that turn, but attack rolls against it have advantage until the start of its next turn.

Innate Spellcasting. Angrath's spellcasting ability is Wisdom (spell save DC 16). Angrath can innately cast the following spells, requiring no material components:

3/day each: polymorph, hold person, haste

2/day: plane shift (eight other creatures and self)

Multiattack. Angrath can make three attacks: two melee attacks with the +3 Warhammer and one Fire Ray attacks.

+3 Warhammer. Melee Weapon Attack: +12 to hit, reach 5 ft., one target. Hit: 17 (2d10 + 7) slashing damage.

Gore. Melee Weapon Attack: +9 to hit, reach 5 ft., one target. Hit: 13 (4d8 + 4) piercing damage.

Fire Ray. Ranged Spell Attack: +8 to hit, range 120 ft., one target. Hit: 10 (5d6) fire damage.

Mogis's Chains of Chaos. As an Action, Angrath can target any creature he can see within 30 ft, that creature must succeed on a Strength saving throw DC 17 or else it becomes restrained; on a successful save nothing happens to the creature. The target creature that fails the save is restrained and cannot use reactions; that creature then immediately takes 6d6 acid, fire, cold or lightning damage (choose one) at the start of its next turn. The restrained creature can attempt another Strength saving throw at the end of its turn to escape Mogis's Chains of Chaos. The restrained creature is released from Mogis's Chains of Chaos automatically if the following occurs: Angrath or the target creature's distance exceeds 30 ft, if the creature becomes immune to the restrained condition, or if the creature is able to teleport away using Teleport, Misty Step or any other similar spell/ability. 

Smokey Step. As a Bonus Action, Angrath becomes wisps of thick black smoke and teleports 60 ft to any location that he can see once per turn. 

Angrath 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. Angrath regains spent legendary actions at the start of its turn.

+3 Warhammer. Angrath makes two melee attacks with his +3 Warhammer.

Cast Haste. Angrath casts the Haste spell.

Twin Fire Ray (2 Actions). Angrath makes two ranged Fire Ray attacks on one or two targets.