Boreas

Born from Ice. Boreas receives no penalty from difficult terrain in deep snow or icy winds.

Innate Spellcasting. Boreas' spellcasting ability is Charisma (spell save DC 18, +5 to hit with spell attacks). He can innately cast the following spells, requiring no material components

At will: detect evil and good, purify food and drink, ray of frost (3rd level)
1/day each: spirit guardians, disintegrate

Rage of Cthulhu. Once a day, Boreas can fly into a rage for 1d4+1 rounds. While raging, Boreas has an advantage on damage rolls and Strength checks and saving throws, but a disadvantage on Wisdom checks and saving throws. Actions marked with a * can only be performed while raging, and he can't use any other action in his rage. When the rage ends, he gains 2 levels of exhaustion.

Son of a Primordial. Boreas has an advantage on saving throws against madness and being charmed or frightened 

Multiattack*. Boreas can make two Phantasmal attack

Bastard Sword: Melee Weapon Attack. +5 to hit, reach 5 ft., 1 target. Hit: 10 (2d8+2) slashing damage.

Ice Dagger. Melee Weapon Attack: +5 to hit, reach 5 ft., 1 target. Hit: 7 (1d10 + 1) piercing damage and 5 (2d4 + 1) cold damage.

Ice Spear. Ranged Weapon Attack: +5 to hit, range 60/120 ft., 1 target. Hit: 7 (1d10 + 1) piercing damage and 5 (2d4 + 1) cold damage.

Phantasmal Bolt*. Ranged Weapon Attack: + 7 to hit, range 120/240 ft, one target. Hit: 8d6 radiant damage.

Phantasmal Eye*. Ranged Weapon Attack: + 7 to hit, range 50/100 ft, one target. Hit: 6d4 radiant damage and the next attack against that creature is a critical hit.

Phantasmal Beam* (Recharge 5-6). Boreas creates a line 100 ft long and 5 ft wide starting at himself. Any creature in the line must make a DC 18 Constitution saving throw and take 8d8 radiant damage on a failed save or half as much on a successful one.

Celestial Stamina: When Boreas is targeted by an attack,  he can use a reaction to move up to his speed and make an Ice Dagger attack. The original attack against him completely misses and costs the attacker its action.