Volar

Mind's Trickery. Volar, at the start of the battle, makes 3 clones around the field that look the complete same with the same actions but not legendary ones, only dispelling when hit.

(How this works is they all have the same initiative, so all the clones essentially take their turn, but only one is the real one that makes the legendary actions. Which is how you can't tell which one is which.)

The True Mind. Once Volar reaches below half HP they cannot gain higher than half HP back, however Volar makes 5 more clones. As well gains the ability to use the legendary action Memory's Hold.

Multi Attack. Volar can make up to two stab attacks 

Stab. Melee Weapon Attack: +10 to hit, reach 8ft, one target. Hit: 12 (2d8 + 3), piercing damage.

Flay. Melee Weapon Attack: +10 to hit, reach 5 ft, one target. Hit: 12 (2d8 + 3) slashing damage. + bleeding for 2 turns.

This is My Domain. Any illusion spells and enchantments do not affect Volar. 

Anger for Fallen Allies.  Unlike his brothers, Volar goes into a rage when one of his brothers is killed.

Volar can make up to two legendary actions

Memory's Hold. Target one creature and if they fail a INT saving throw DC 13 take 20 if failed, and half in success.

Mind Wrencher (costs 2 actions). All non-Deos creatures make a INT saving throw DC10 and if failed take 15 psychic damage, if succeeded, then they take 8 psychic damage.