Archmage Seraphina

Spellcasting. Archmage Seraphina is an 18th-level spellcaster. Her spellcasting ability is Intelligence (spell save DC 20, +12 to hit with spell attacks). She has the following wizard spells prepared:
Cantrips (at will): fire bolt, mage hand, prestidigitation, ray of frost
1st level (4 slots): detect magic, mage armor, shield, sleep
2nd level (3 slots): detect thoughts, mirror image, misty step
3rd level (3 slots): counterspell, dispel magic, fireball
4th level (3 slots): banishment, dimension door, greater invisibility
5th level (3 slots): cone of cold, scrying, telekinesis
6th level (1 slot): chain lightning, globe of invulnerability
7th level (1 slot): forcecage, teleport
8th level (1 slot): mind blank, power word stun
9th level (1 slot): time stop, wish

Spellcasting Mastery. Archmage Seraphina's concentration on spells can't be disrupted as a result of taking damage. She also has advantage on saving throws to maintain concentration.

Spell Resistance. Archmage Seraphina has advantage on saving throws against spells and other magical effects.

Staff: Melee Weapon Attack: +6 to hit, reach 5 ft., one target. Hit: 3 (1d6) bludgeoning damage, or 4 (1d8) bludgeoning damage if wielded with two hands.

Arcane Recovery (1/Day): As a bonus action, Archmage Seraphina can recover expended spell slots. She can recover a total level of spell slots equal to 10.

Arcane Deflection. When Archmage Seraphina is targeted by an attack or fails a saving throw, she can use her reaction to gain a +4 bonus to her AC or saving throw.

Legendary Resistance (3/Day): If Archmage Seraphina fails a saving throw, she can choose to succeed instead.