User blog comment:AdventuringStar/Where's The Lich? (discussion)/@comment-6512164-20131220174201

The Lich is alive.

I think that prismo said that after the wish is made, the person who made the wish goes to the wish's alternate reality. Since the Lich asked for Finn and Jake to go back to Ooo, I think that he is somewhere else, plotting his revenge.