I've been running around in the maze for hours. I killed three serpant caretakers but none had the skull key. Where is this dude hiding?

I had a lot of trouble in this area. I finally mapped the elevators on a piece of paper showing the four diamond rooms and which lift connected to which other lift (ignoring the tunnels between them). And there he was with the needed key. Good lick!

When you get to the room that has two doors with skull levers (the only choice you have initially), go through the right-hand door. There's nowhere else to go from that doorway but straight to the Serpent Master. Follow the passageway up through several levels and there he will be in a room with several passages leading off it.

I found him in the maze just by running around like a loonie and falling down a chute that turned a few times. He gives you a little speech about being the final sentry to Elyssia and asks you two questions about being a serpent priest. Answer yes and then none and he will give you the skull key. Hit the switch on the wall and the two lifts will begin to function. There is a chest here as well. And I killed him after he gave me the key.

I had tried just killing him once before and he didn't drop the key. But after answering the questions he gave it willingly. Maybe I just couldn't see it on the floor but I doubt it.

Good luck on finding him. I hated that place.