Azig'orath

Shapeless: Azig'orath's form can be easily changed, polimorphs having a duration increase of 1d8 rounds.

Natureless:  If Azig'orath is killed, his consciousness will wonder around until he can replace the nature he lost, that proccess can take from 1d10 minutes to 1d8 weeks, having the threat of it being pulled into any plane by the smallest of openings.

Shapeless Shifting: Azig'orath can take the form of any creature he holds knowledge of at will, taking in all of their characteristics except for alingment and lair actions.

Controlled Form: As a bonus action, Azig'orath can make a telepathic connection with any sentient creature within 60ft of him, changing his form to the thing his target would hate encountering most. (note: this is simply an appearance switch, not carrying any benefit that form may have.)

Unwelcomed Attack. Azig'orath can use counterspell as a 9th level spell, using a DC of 8. How many times he can do this per day is based on his current Challenge rating.

Azig'orath form is at his complete wim, and so he gains the ability to control it fully with 3 legendary actions.

Bending Shape (Costs 2 Actions). Azig'orath will send forth a barrage of 4d8 spikes directly infront of him or his back doing 1d6 each or heal himself for 4d10 of damage.

Untrue Nature (costs 1 action). Azig'orath's nature has been lost, but he may use another creature's nature as his own, and any creature that shares that nature within 60 ft will receive 1 level of exhaustion. (nature being creature type, i.e. if he's a dog a T-rex might pass out.)