Hey! I remember someone in this forum once did a mock-up of a green Exegol, but I can’t remember who was.
I was thinking about that idea of suggesting Palpatine kept himself alive through arcane methods, maybe involving secrets learned from the Nightsisters. That could be accomplished by surrounding the ailing Palpatine and his machinery with a faint green mist, plus Nightsister magic sound effects pulled from the Clone Wars show.

Also, maybe that green color and magic SFX could be applied to the Force-draining when Palpatine restores himself. I was watching the original movie with my family and it was kind of funny for us how the draining effect looked like a Dementor’s kiss 😄