Archfey Iteros

Fey Magic Resistance. Iteros is immune to charm, and magic can't put him to sleep. He has advantage on saving throws made against spells and other magical effects.

Potent Archfey Spells. As a master of his spells and Archfey of his court, Iteros can bend the rules of magic to his will. He can ignore certain spell requirements, such as casting time, duration, and number of targets, provided he is not in combat. If he attempts to bend the rules of a spell in combat, he must make an ability check using his Charisma. The DC for this is 12 + the spell's level. He can also cast spells not listed below, such as Sending and Scrying, as a ritual, and ignores criteria for targets being on the same plane of existence. He can also cast two spells per round in the following situations: casting Counterspell while casting another spell, casting a spell as an action and another as a bonus action, and casting a spell or cantrip as a hasted action if he is hasted. He adds his Charisma modifier to the damage dealt with his Eldritch Blast. Iteros has advantage on Constitution saving throws to maintain concentration.

Spellcasting. Iteros is a 20th-level spellcaster. His spellcasting ability is Charisma (spell save DC 21, +13 to hit with spell attacks). Iteros knows the following spells:
Cantrips (at will): Eldritch Blast, Mage Hand, Minor Illusion, Prestidigitation

1st level (4 slots): Charm Person, Dissonant Whispers, Shield

2nd level (3 slots): Invisibility, Mirror Image, Misty Step

3rd level (3 slots): Counterspell, Fear, Hypnotic Pattern

4th level (3 slots): Dimension Door, Greater Invisibility, Polymorph

5th level (3 slots): Dominate Person, Hold Monster, Modify Memory

6th level (2 slots): Mass Suggestion, True Seeing

7th level (2 slots): Etherealness, Magnificent Mansion, Project Image

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

9th level (1 slot): Foresight, Weird

Legendary Resistance (3/day). If Iteros fails a saving throw, he can choose to succeed instead.

Multiattack. Iteros can use his action to cast a cantrip or a 1st-level spell, and he can make one attack with the Staff of Stellunos.

Staff of Stellunos. Melee Weapon Attack: +9 to hit, reach 5 ft., one target. Hit: 5 (1d8 + 3) bludgeoning damage. 

Eldritch Blast (4 Beams). Ranged Spell Attack: +13 to hit, range 120 ft., one to four targets. Hit: 12 (1d10 + 7) force damage (per beam). Each beam requires a separate attack roll.

Misty Step. Iteros casts Misty Step, using a spell slot.

Counterspell. Iteros can attempt to suppress a spell being cast, using a spell slot.

Shield. Iteros can cast shield as a reaction to being target with an attack that would hit him, increasing his armor class to 23, and using a spell slot.