Now, I'm confused, which hatch? the one in the castle? No you can't enter from there. you free Zandalor via Ars magicana/Rivertown sewers

http://kiya1.via.t-online.de/images/Div_Arssew.jpg

Well, having NO pyramid with you was not part of the game plot. If you carry one with you now, what happens? Don't worry, Raze has a download fix for lost pyramids - BUT I'd wait in your case and free Z. first. He'll teleport you to an area where the imp has your pyramids (hopefully).
Kiya