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

Multiattack. The archmage makes four Arcane Burst attacks.

Arcane Burst. Melee or Ranged Attack Roll: +9, reach 5 ft. or range 150 ft. Hit: 27 (4d10 + 5) Force damage.

Spellcasting. The archmage casts one of the following spells, using Intelligence as the spellcasting ability (spell save DC 17): At Will: Detect Magic, Detect Thoughts, Disguise Self, Invisibility, Light, Mage Armor (included in AC), Mage Hand, Prestidigitation 2/Day Each: Fly, Lightning Bolt (level 7 version) 1/Day Each: Cone of Cold (level 9 version), Mind Blank (cast before combat), Scrying, Teleport

Misty Step (3/Day). The mage casts Misty Step, using the same spellcasting ability as Spellcasting.

Protective Magic (3/Day). The archmage casts Counterspell or Shield in response to the spell's trigger, using the same spellcasting ability as Spellcasting.