Brainiac

 Brainiac automatically succeeds all intelligence based rolls 

Tentacle thwap - melee attack reach of 50 feet plus  7d4 bludgeoning can target 3 creatures in one attack 

Tentacle grab - the target makes a dex save DC 23 on a success on a failure that are raised into the air by one of brainiacs tentacles and affected by the restrained status while held and in the air brainiac can do one of the following things 

Throw the target is thrown 80 feet and takes 24 bludgeoning damage 

Tear the target makes a constitution saving throw DC 19 and take 100 damage on a fail and 50 on a success 

Probe brainiac can probe the creatures brain gaining all of its knowledge until the point of probing this deals 10 psychic damage the first time it's used every time the creature gets probed the damage doubles 

Brainiac can also choose to leave them restrained until on the targets turn they succeed a DC 17 strength save with every failure the DC raises by 2 and the target takes 5 damage the first time the damage doubling every constriction this does not carry over to the second time the creature is restrained 

5 creatures can be tentacle grabbed at once however brainiac can only use his grab action on one while nothing happens to the others 

Psychic dominion unlimited range The first time this ability is used the target takes 10 psychic damage and brainiac begins the process of taking over a creatures mind 

Phase 1 the target has disadvantage on wisdom and intelligence checks and saves 

Phase 2 14 psychic damage and Brainiac can freely use the spell command on the target with a 100% chance of success 

Phase 3 Brainiac can use an action to make the target 40 psychic damage 

Phase 4 brainiac can use a turn to take complete control of a character for their next two turns 

Psychic crush  if psychic dominion gets to what would be phase 10 Brainiac can use an action to insta kill the target 

Psychic scream plus 12 to hit 4d6 plus 8 psychic damage 

Disarm as a reaction brainiac can roll tentacle thwap against the  players attack roll if brainiac rolls higher the weapon goes flying across the room 

Brainiac can use 4 legendary actions a day 

Override Brainiac hacks any technology within 10 feet of him 

Psychic dominion

Tentacle grab

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Mythic Action Name (Costs # Actions). Enter the description for your mythic action.