Cas Turnhall

Magic Resistance. Cas has Advantage on saving throws against spells and other magical effects.

Portent. Glimpses of the future begin to press on your awareness. Whenever you finish a Long Rest, roll two d20s and record the numbers rolled. You can replace any d20 Test made by you or a creature that you can see with one of these foretelling rolls. You must choose to do so before the roll, and you can replace a roll in this way only once per turn. Each foretelling roll can be used only once. When you finish a Long Rest, you lose any unused foretelling rolls.

Multiattack. Cas makes four Arcane Burst attacks or two Arcane Burst attacks and one spellcasting.

Arcane Burst. Melee or Ranged Attack Roll: +9, reach 5 ft. or range 150 ft. Hit: 27 (3d10 + 6) Force damage.

Spellcasting. Cas casts one of the following spells, using Intelligence as the spellcasting ability (spell save DC 19):

At Will: Detect Magic, Detect Thoughts,Invisibility, Mage Armor (included in AC), Mage Hand
4/Day Each: Enemies Abound, Fly, Fireball, Dispel Magic, Hypnotic Pattern, Slow
3/Day Each: Phantasmal Killer, Greater Invisibility, Ice Storm
2/Day Each: Synaptic Static, Wall of Force
1/Day Each: Finger of Death 

Misty Step (At Will). The mage casts Misty Step, using the same spellcasting ability as Spellcasting.

Counterspell (3/Day). Cas casts Counterspell in response to the spell’s trigger, using the same spellcasting ability as Spellcasting.

Shield (At Will). Cas casts Shield in response to the spell’s trigger, using the same spellcasting ability as Spellcasting.