Aziel the Arrogant

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

Spellcasting. The [Aziel] is a 4th level spellcaster. Its spellcasting ability is [5]

 Spell save DC 18, +10 to hit with spell attacks

The [Aziel] has the following [Warlock] spells prepared:
Cantrips (at will): [Toll the Dead], [Fireball] 
1st level (4 slots): [Charm Person], [Wall of Fire]c 

2nd level (3 slots): [Misty Step]BA, [Invisibility]A,c

3rd level (2 slots): [Counter spell]R

4th level (1 slot): [Dimension Door]A

5th level (1 slot): [Hold Monster]A,c

 Scimitar. Melee Weapon Attack: +8 to hit, reach 5 ft., 1 target. Hit: 7 (1d6 + 3) [slashing] damage. 

Toll the Dead. 60ft. WIS Saving Throw. DC 18. 2d8 or 2d12. ACTION.

Fireball. 150ft. 20ft Sphere. DEX Saving Throw. DC 18. Half on a success. 8d6. ACTION.

Charm Person. 30 ft. WIS Saving Throw. DC 18. Charmed. 1 hour. ACTION.

Wall of Fire. 120ft.60x20, 1ft thick. DEX Saving Throw DC 18. Half on a success. 5d8. ACTION. C

Counter Spell: Aziel can cast counterspell as a reaction up to 3 times, from the Legendary actions slots.

Aziel can take 3 legendary actions per round.

Blindness/Deafness (Costs 1 Actions). You can blind or deafen a foe. Choose one creature that you can see within range to make a Constitution saving throw. If it fails, the target is either blinded or deafened (your choice) for the duration. At the end of each of its turns, the target can make a Constitution saving throw. On a success, the spell ends.

Regeneration (Costs 2 Actions). Aziel regains 20 hit points at the start of his turn. If he takes radiant damage, this trait doesn't function at the start of his next turn. Aziel dies only if he starts his turn with 0 hit points and doesn't regenerate.