Archmage of winter

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

Spellcasting. The archmage is an 18th-level spellcaster. Its spellcasting ability is Intelligence (spell save DC 19, +11 to hit with spell attacks). The archmage can cast disguise self and invisibility at will and has the following wizard spells prepared:

Cantrips (at will): frostbite, light, mage hand, ice weapons(multiattack), ray of frost

1st level (4 slots): detect magic, identify, detonating shard, frost fingers

2nd level (3 slots): detect thoughts, conjure ice beast, misty step

3rd level (3 slots): counterspell, fly, icy pulse

4th level (3 slots): banishment, fire shield, frost armor*

5th level (3 slots): cone of cold, icicle explosion, wall of force

6th level (1 slot): glaciers

7th level (1 slot): whirlwind

8th level (1 slot): mind blank*

9th level (1 slot): time stop

*The archmage casts these spells on itself before combat.

Artic aura. The archmage can use its reaction to gain immunity to material and fire attacks for one turn by freezing them. This ability recharges after a long or short rest.

Dagger. Melee or Ranged Weapon Attack: +6 to hit, reach 5 ft. or range 20/60 ft., one target. Hit: 4 (1d4 + 2) piercing damage.