We dispel his magic, silence his throne room, but he keeps innately teleporting around. Combat keeps getting bogged down by this house rule? where he breaks movement into the segments so every player's action takes 10x as long to resolve. It's 7:15 and we pin him in a room. I can't get in...

So at 7:20 I drop. I tell the GM thanks for running I had fun, hand my character to the cleric who has been stunned by Power Word Stun and go get some dinner. After dinner I ran into the wizard and asked how it went. I left 20 minutes too soon, but the party was successful and defeated the lich.