I also need to figure out how this arrogant selfish sorceress Xandala interacts with the vainglorious Medusa Queen. They're both vain strong personalities.
In her hanging garden lair, the Medusa Queen is more powerful, but Xandala is more intelligent, more skilled at deception/flattery, and a better judge of character (she'd quickly realize that the Medusa Queen's grasp on reality is tenuous).
Might Xandala sweet talk the Medusa Queen somehow?
My interpretation of the Medusa Queen Zalkoré varies a bit from ToA, probably elevating her from CR 6 to CR 8 or 9:
- she is a 7th-level wild magic sorcerer with chaos bolt, fog cloud, shield, alter self, hold person, blink, enemies abound, and confusion
- her hanging gardens are a limited wild magic zone where every spell she casts triggers a wild magic surge (from a custom table adapting the one in the PHB)
- she has Otherworldly Perception (letting her see invisible/ethereal creatures)
- she is fused with a yellow musk creeper and has its Touch and Yellow Musk 3/day (making her a monstrosity/plant hybrid)
- she has lair actions including Absorb Plant Creature, Conjure 6 Yellow Musk Zombies, Tides of Chaos, and Zombie Eruption