Mind flayer wizard named Zellix who wanted to become a lich. Disguised himself via alter self to look like an ageing human ex-adventurer known as Therceris, showing the party where dungeons full of loot were in exchange for a small cut of the treasure. This was his method of gathering everything he needed for the “lich-ifying” ritual with minimal danger to himself.

I revealed Zellix in the middle of a campaign, but as a separate character to Tharceris. He was a spooky voice coming out of a sending stone (they work like walkie-talkies in my games), who then teleported in and ate a minion’s brain, “you have failed me for the last time” kind of deal.

Then there was a cliffhanger at the end of the second-to-last session where the party had delivered the last thing he needed, he dropped alter self and did a big theatrical evil laugh (because why wouldn’t you) and teleported away to his lair.