Beaa'vaaraa, the architect

Instinctive charm. if a creature makes a melee attack against Beaa, he can chose to have the attacker make a DC 24 wisdom saving throw or hit another target within attack range, if there is no other creature this does nothing

Split enchantment. if Beaa casts a 1st level enchantment spell which targets only one creature* he can chose to have it target another creature as well

Alter memories. when a charm cast by Beaa wears off the charmed creature must succeed in a DC 24 wisdom saving throw or lose 4 hours of memories, erasing their memories of what happened when charmed

Arcane savegery. if Beaa rolls a 1 or 2 on a spell damage roll he can reroll the dice once and has to keep that new number

Innate Spellcasting. Beaa's innate spellcasting ability
is wisdom (spell save DC 24, +19 to hit with spell attacks). It can innately cast the following spells, requiring no material components:
at will: comprehend languages, detect magic
7/day each: fireball, identify, see invisibility, arcane eye, polymorph
3/day each: haste

Magic items. Beaa owns an extensive list of magic items including
deck of illusions: Beaa draws a card from the deck, creating an illusion depending on the card
broom of flying: has a flying speed of 50ft
bag of tricks: the bag has 3 orbs inside of it, when throwing an orb Beaa rolls a d8 and summons a jackal on 1, ape on 2, baboon on 3, axe beak on 4, black bear on 5, giant weasel on 6, giant hyena on 7 and tiger on 8
eye of the game changer: 5 times a long rest Beaa can force a reroll on any roll, whether his or another persons
eye of the appraiser: Beaa can instantly tell the price of an object with a 30% margin of error and can instantly identify what object he's looking at
the hand of Vecna (copy): the user can add 1d6 to any damage roll, add 2d6 cold damage to melee attacks, the hand has 8 charges and can cast finger of death for 5 charges, cast sleep for 1 charge and teleport for 3 charges
the eye of Vecna (copy): the user has x-ray vision and the item has 8 charges and can cast the clairvoyance spell for 2 charges, cone of cold for 1 charge, disintegrate for 4 charges, dominate monster for 5 charges, eyebite for 4 charges and crown of madness for 1 charge
with both the hand and eye of Vecna, Beaa can't be surprised, heals 1d10hp per turn and cast wish once every 30 days
the journal of Vecna. this item has has 7 charges and can expend a charge to ask the book any question, in which the book will give a detailed answer in the form of text, the user can regain charges by correctly answering one of the journals questions
the heart of vecna. the user can cast the soul cage spell without any spell slots and roll 1d6, on a 6 the user can do so again and regain 2d12 hit points every 10 minutes
the gauntlet of vecna. anything that was summoned by the user deals an extra 2d6 cold damage and the gauntlet has 8 charges and can cast dance macabre for 5 charges, negative energy flood for 4 charges, fireball for 3 charges, animate dead for 2 charges and shield for 1 charge

Magic resistance. Beaa has advantage on all saving throws against spells and other magic effects

Legendary Resistance (3/Day). If Beaa fails a saving throw, he can choose to succeed instead.

Meaning in absurdity. if Beaa rolls a nat 1 on saving throws he looses a damage resistance of his choice

Siege monster. beaa deals double damage to inanimate objects

Obliterate. Creatures killed by force damage dealt by Beaa leaving no trace of a body behind, and can only be restored to life with a wish or true resurrection spell.

Dimension warp. at the beginning of his turn Beaa can choose a 10x10 area where if anyone steps inside they take 5d12 damage of his choice, this area disappears on his next turn and the warp can not hurt Beaa

Hyperdimensional. At the beginning of each of its turns, if Beaa has a speed greater than 0, he can choose his size: Medium, Large, Huge, Gargantuan or Colossal. If his new size encompasses other creatures, those creatures must make a DC 20 Dexterity saving throw. On a successful save, the creature can choose to be pushed back or to the side until it is no longer in the same space as Beaa. A creature that chooses not to be pushed, or cannot reach an unoccupied space, suffers the consequences of a failed saving throw. On a failed save, the creature takes 25 (4d10 + 10) force damage and is restrained. The creature remains restrained until it no longer occupies a space with Beaa, or until it escapes. To escape, the creature takes an action to make a DC 20 Strength check. On a success, the creature enters a space of its choice within 5 feet of Beaa.

 Bonded with the beyond. after absorbing the false Mystra he absorbed all of her raw power, giving him a power inside of him which functions the same way as a magic item,
lets the user cast create minor paradox using 1 charge
lets the user cast befuddle magic using 1 charge
lets the user cast fire shield using 1 charge
lets the user cast compress gravity using 1 charge
any holy water within 10 feet of Beaa turns into water
it holds 500 charges and let's Beaa cast the following spells
misty step (2 charges), thunder step (3 charges), dimension door (4 charges), far step (5 charges), teleportation circle (5 charges), word of recall (6 charges), teleport (7 charges), plane shift (7 charges), gate (9 charges)
wish (9 charges) (can not be used to kill others)
destructive wave (5 charges), globe of invulnerability (6 charges, antimagic field (8 charges), invulnerability (9 charges), meteor swarm (9 charges)
gift of alacrity (1 charge), fortunes favor (2 charges), temporal shunt (5 charges), time ravage (9 charges), time stop (9 charges), foresight (9 charges)
confusion (4 charges), geas (5 charges), dream (5 charges), rary's telepathic bond (5 charges), modify memory (5 charges), otto's irresistable dance (6 charges) antipathy/sympathy (8 charges), telepathy (8 charges), feeblemind (8 charges), psychic scream (9 charges), weird (9 charges)
magic jar (6 charges), soul cage (6 charges), resurrection (7 charges), tether essence (7 charges), true resurrection (9 charges), astral projection (9 charges)

Spellcasting. Beaa'vaaraa is a 20th-level spellcaster. Its spellcasting ability is intelligence (spell save DC 24, +19 to hit with spell attacks). Beaa'vaaraa has following wizard spells prepared:
Cantrips (at will): abacus, air bolt, arcane word: mirage, card trick, fire bolt, nyxy's rainbow ray, prestidigitation, chill touch, mage hand, infestation
1st level (8 slots): absorb elements, acceleration, air blasting, air walk, amplify damage, amplify magic, amplify pain, analyze, animate claw, animate corpse, animate lesser dead, animate shadow, arc strike, arcane blast, arcane mark, arcane seeing, arcane word: barrier, arcane word: barta, arcane word: burn, argh!?, arguments against design, ataxia, bewitch, black flame, burning hands, cause fear, chameleon, charm person, chromatic orb, chromatic strike, cinderfall, conjure arms, conjure demon, corpse bomb, corrosive mist, demon skin, detect magic, disguise self, deja vu, explosion, earth tremor, false life, feather fall, fog cloud, grease, hideous laughter, identify, jump, longstrider, mage armor, magic missile, power word: repel, power word: trip, radiant multi-beam, riddle lock, shield (at will), silent image, thunderwave, ward, witch bolt, fog cloud, sleep, tasha's hideous laughter
2nd level (6 slots): blur (at will), infer intentions, mirror image, detect thoughts, blindness/deafness
3rd level (6 slots): animate dead, arcane bomb, arcane clap, arcane spear, army of the dead, arrest wizard, blink, breathtaking, chaos bomb, chrono lock, conjure imps, conjure shadow clone, counterspell, create soul gem, dark wings, fear, fireball, fly, gaseous form, haste, lightning bolt, mage's shield, magic circle, slow, nondetection
4th level (6 slots): aarion's arcane image, abi dalzims horrible witching, adcan's lightning step, anesthesia, arcane eye, aura of evasion, banishment, black tentacles, blight, bloated corpse, bolster undead servant, bomb transmutation, catch/release spell, charm monster, confusion, conjure minor elementals, conjure monstrosities, desecrate, dimension door, greater invisibility, phantasmal killer, polymorph, spell mege, summon aberration, summon construct, summon greater demon, madam mixtreths true love, throes of extacy
5th level (6 slots): abendroth's titanicfication, aberrant call, aberrant whispers, absolute drain, absorb life, absorb spell, acid fog, aging touch, alter dead, alter timeline, arcane armor, arcane hand, arcane vigor, arms of the grave, chaos unleashed, circle of necromancy, cloudkill, cone of decay, control lava, create timegate, danse macabre, dominate person, enervation, geas, hold monster, mass life drain, minor time stop, mislead, modify memory, negative energy flod, power word: stop, scrying, skill empowerment, telekinesis, teleportation circle, time loop, transmute rock, wall of force, apparition of the grave, electric overflow, scrying, cloud kill, polymorph
6th level (4 slots): aarion's replenishing infusion, abi dalzim's soulfire, accelerated aging, akham's mummification, alter form, altered destiny, animate beholder, animate prosthetic, anthropromorph, arcane gate, aural lance, bahseth's soul signature, bend blood, cataclysmic eruption, chain lightning, circle of death, cloak of gloriousness, create homunculus, create paradox, create undead, crushing despair, death gaze, demonic mantle, disintegrate, eyebite, globe of invlulnerability, greater absorb elements, grey's time toll, instant summons, magic jar, mass suggestion, mental prison, otto's irresistable dance, power word: incinerate, programmed illusion, scatter, soul cage, summon fiend, summon an army, true seeing, chain lightning, soul cage
7th level (4 slots): acid swamp, alter gravity, animate dread warrior, animate major undead, antimagic curse, army of the night, bites the dust, clownification, conjure hezrou, conjure voidborn, create doppelganger, create helmed horror, crushing prison, curse plague, deep sleep, delayed blast fireball, delayed damage, empower form, etherealness, fear wave, finger of death, grasp heart, magnificent mansion, most vicious mockery, plane shift, power word: void, teleport, create death knight, divine word, power word: pain
8th level (2 slots): abhorrent scarring ritual, abi-dalzims horrid wilting, abyssal empowerment, advanced warning, age/rewind person, aging, altered resurrection, antipathy/sympathy, aura of the unremarkable, clone, control weather, dark rebirth, demiplane, dominate monster, feeblemind, glimpse of the void, grasping heart, maddening darkness, magic item supercharger, maze, mind blank, mind erosion, paragon of chaos, power word: pleasure, power word: stun, soul trap, telepathy, maze, clone
9th level (2 slots): absolute death, absolute submission, absorb true life, advanced teleport, amnesia, animate killing field, arcane ascension, banak's arcana form, become dragon, bestow plague, bind to service, black ice, blood contract, breakson's bolt, change your mind, conjure castle, create, dark lightning apocalypse, gate, greater time stop, invulnerability, power word: kill, power word: yeet, psychic scream, spellfill, true polymorph, wish, conquer dragon, time stop

Hypnotic gaze. Beaa can pick any creature within 10 feet which he can see, that creature has to make a DC 24 wisdom saving throw or become incapacitated and visibly dazed, the creature can repeat these saving throws during their turns.

Punch. Melee Weapon Attack: +18 to hit, reach 5 ft., 1 target. Hit: 13 (2d8 + 10) bludgeoning/cold damage. once per day he can force a creature to go unconscious with this action and once per day he can make the hit creature make a DC 15 constitution save or die immediately 

Force blast. Ranged Spell Attack: +15 to hit, reach 200ft, one target. Hit: 72 (8d12 +12) force damage

Dimension rake. Melee Magic Attack: +15 to hit, reach 15 ft, one target. Hit: 20 (3d12 + 12) slashing damage and 20 (3d12 +12) force damage

Psychic force (1/3 turns) Area of Effect Spell Attack: Beaa summons knowledge he has gained after bonding with Mystra and releases the knowledge in a pure, magical force that rips through the dimensions. All creatures inside of a 60ft cone must make a DC 23 Wisdom saving throw or take 6d12 + 6 force damage and 6d12 +6 psychic damage on a fail and half damage on a success.

Corrupted Knowledge (1/3 Turns) Beaa reaches into the inner recesses of his mind and targets a creature it can see. The target must choose a non-physical damage type and must succeed a DC 23 Wisdom saving throw or take 6d12 + 12 psychic damage and 6d12 + 12 of the damage type the target chose. Half damage if they succeed.

beaa'vaaraa can make 2 legendary actions but must make them as a reaction during another creatures turn. He regains spent legendary actions at the beginning of his next turn.

Centrality Beaa sends his brain into overdrive, calculating 100s of possible actions within fractions of second. Until the start of its next turn, Beaa gains a 30ft aura that gives attacks disadvantage.

Diffusion (Only after Centrality is used) Beaa tries telepathically sending all of the calculated knowledge of the fight, trying to fry his enemies brains. Any creature within 30ft must make a DC 23 Intelligence saving throw or take 50 psychic damage on a fail and half on a success. Beaa then loses the effects of Centrality.

Time and Eternity (Only can be used when at  200 or lower hit points) beaa, having been pushed to his limit, uses 100% of all the arcane and mental capabilities he has, tearing through the concept of time and creating his own. Beaa then moves among the affected creatures as they are frozen in time and touches them, dealing damage based on their weaknesses. All creatures must roll a d6 and make a DC 23 saving throw depending on their roll. On a fail they take 20d10 damage based on their saving throw and lose all movement and half damage and half movement on a success until the start of Beaa's next turn. This ability cannot be used again for another two rounds.

1 = Wisdom/Psychic

2 = Intelligence/Radiant

3 = Charisma/Necrotic

4 = Strength/Force

5 = Constitution/Poison

6 = Dexterity/Cold