Absolution: If Absalom would be reduced to 0 hit points, he automatically casts Absalom's Avatar. When he does this, his hit points regenerates to 1296, he regains all uses of his Legendary Resistance, and he gains access to his Mythic Actions. He also regains all of his spent spell slots.

Legendary Resistance [9/Day]: If Absalom fails a saving throw, he can choose to succeed instead.

Magic Resistance: Absalom has advantage on saving throws against spells and other magical effects. He also has a +3 to all saving throws against spells.

Arcane Pantomath: Absalom can identify a spell without using an action if he can see or hear it being cast, or if he can see or hear its ongoing magical effects at any point during its duration. In addition, Absalom instantly learns the properties of a magic item if he can see the item. 

Absalom the Mad: Absalom can attempt to cast a spell from the wizard spell list that he doesn't have prepared by making a DC 30 Intelligence (Arcana) check and expending a spell slot as normal. On a success, he casts the spell. On a failure, both his action and the spell slot are wasted.

Supreme Arch-wizard: Absalom can maintain concentration on three spells at a time. They can be three instances of the same spell, or different spells. If he casts a fourth spell requiring concentration, he chooses which of the three prior spells to new spell will replace. In addition, he has advantage on saving throws to maintain concentration on spells.

Spellcasting: Cantrips (at will): mage hand, minor illusion, prestidigitation, thunderclap, toll the dead

1st level (4 slots): absorb elements, mage armor, magic missile, shield

2nd level (3 slots): blindness/deafness, enlarge/reduce*

3rd level (3 slots): counterspell, dispel magic enemies abound* slow*

4th level (3 slots): phantasmal killer*, polymorph*, sickening radiance*

5th level (2 slots): enervation*, far step, passwall, telekinesis*, transmute rock

6th level (2 slots): Chain lightning, disintegrate, globe of invulnerability*, investiture of wind*

7th level (2 slots): Crown of stars, Reverse gravity*

8th level (2 slots): Illusory dragon* Maddening darkness, Mind blank, Sunburst

9th level (2 slots): Meteor swarm, Prismatic wall, Shapechange*, Wish

10th level (1 slot): Create Ioun Stone

11th level (1 slot): Create Mythallar

12th level (1 slot): Absalom's Avatar

*Concentration spells

Cast a Spell: See traits.

Spellcasting: Whatever spells are BAs.

Spellcasting: 

1st level (4 slots): Shield

3rd level (3 slots): Counterspell

Absalom can take 3 legendary actions, choosing from the options below. Only one legendary action can be used at a time, and only at the end of another creature's turn. Absalom regains spent legendary actions at the start of each of his turns. 

Cast a Spell (Cantrip-5): Absalom casts one spell under 5th level. 

Cast a Spell (Costs 2 Actions) (6-11): Absalom casts one spell from levels 6 to 11.

If Absalom used his Absolution skill in the last hour, he can use the options below as  legendary actions.

Magicka Monster (Costs 2 Actions): Absalom expends a spell to create a living spell which follows his orders and disappears after 5 rounds. (See Eberron: Rising From the Last War)

Arcane Absorbtion (Costs 3 Actions): Absalom's Arcane Sigil  lights up with dark purple arcane energy, and he starts a chant in Arcano. This chant lasts for 3 turns, and he cannot perform any actions during these turns. When he finishes, he rolls a d20, and he regains any amount of spell slots equal to his roll.