Archmage Augustrum, Ascended Avatar of the Arcane

Anathematic Secrecy. Augustrum can't be targeted by any divination magic or perceived through magical scrying sensors unless he wishes to be targeted or perceived.

Legendary Resistance (3/day). If Augustrum would fail a saving throw, it can choose to succeed instead.

Discorporation. When Augustrum drops to 0 hit points or dies, his body is destroyed but his essence travels back to beyond the cosmos, and he is unable to take physical form for a time.

Divine State. Augustrum is immune to spells of 6th level or lower unless he wishes to be affected, and has advantage on saving throws against all other spells and magical effects. Additionally, Augustrum is immune to any spell or effect that would alter his form, as well as those that would read his thoughts, determine if he is lying, or otherwise influence his thoughts or behavior, unless he wishes to be affected.

Spellcasting. Augustrum is a 20th-level spellcaster. His Spellcasting ability is Intelligence (spell save DC 27, +19 to hit with spell attacks). The Avatar has all wizard spells prepared at all times, but still requires material components for spells that have a listed cost. Augustrum regains all of its expended spells lots after a short rest.

-Cantrips (at will)

-1st level (at will)

-2nd level (at will)

-3rd level (at will)

-4th level (6 slots)

-5th level (5 slots)

-6th level (5 slots)

-7th level (4 slots)

-8th level (4 slots)

-9th level (4 slots)

Arcane Protection. Augustrum is permanently under the effects of the Mage Armor and Shield spells as long as he is conscious, increasing his AC by 8 and causing him to take no damage from the Magic Missile spell.

Magic Item Master. Augustrum can use any magical item that requires attunement as if he were already attuned to it, even if another creature is attuned to it. Additionally, Augustrum is immune to the effects of curses and detrimental properties of magical items he uses, unless he wishes to be affected. When Augustrum uses a magical weapon to make an attack, he may use his spell attack modifier to make that attack.

Mind of a God. Augustrum may concentrate on up to three different spells at once, and has advantage on saving throws against losing concentration from taking damage. Also, Augustrum can cast 10th level spells without the help of other spellcasters, as long as he has sufficient ninth-level spell slots to spend on it. If unspecified, then Augustrum will use three 9th level spell slots to cast it.

Mystic Might. Augustrum’s weapon attacks are magical, and he may use his intelligence modifier in place of its strength modifier for all weapon attacks.

Multiattack. Augustrum makes two prismatic longsword attacks. 

Prismatic Longsword. Melee Weapon Attack: +19 to hit, reach 5 ft., one target. Hit: 14 (1d8 + 10) slashing damage or 15 (1d10 + 10) slashing damage if wielded with both hands, plus 31 (7d8) damage of any type.

Teleport. Augustrum magically teleports, a long with any equipment he is wearing or carrying, to any location that he has seen before on the same plane of existence.

Arcane Influence (5/day). A creature that Augustrum can see must make a DC 27 Constitution saving throw, or suffer one of the following effects:

1:  the creature becomes magically incapacitated and restrained for 2d4 rounds. At the end of the creature's turns, it may make a DC 25 Strength saving throw in order to break free.

2:  the creature becomes unable to cast spells for 2d4 rounds. At the end of the creature's turns, it may make a DC 25 Wisdom saving throw in order to overcome the block.

3: the creature drops what it is holding and becomes frightened for 2d4 rounds. While frightened in this way, the creature must take the dash action and move away from Augustrum by the safest possible route on each of its turns, unless there is nowhere to move. If the creature ends its turn in a location where it doesn't have line of sight to Augustrum, and at the start of any of the creature's turns in which it doesn't have line of sight to Augustrum, the creature can make a DC 25 Wisdom saving throw. On a success, the effect ends.

4: the creature takes 20 force damage, and for 2d4 rounds, whenever the creature makes an attack roll against Augustrum, it takes 20 force damage. Additionally, while this effect is active, the affected creature makes attack rolls against Augustrum with disadvantage. On the end of the creature's turns, it can make a DC 25 Constitution saving throw, ending the effect on a success.

The same creature cannot be the target of more than one effect at a time, nor can it be afflicted with the same effect twice in a row.

Augustrum 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. Augustrum regains spent legendary actions at the start of its turn.

Flicker. Augustrum casts Misty Step without consuming a spell slot.

Longsword (costs 2 actions). Augustrum makes one Longsword attack.

Cast Spell (Costs 2 actions). Augustrum casts a spell of 5th level or lower.

Arcane Influence (costs 3 actions). Augustrum uses his Arcane Influence ability.