Weird Stronghold Raids

There could be weird Strongholds never seen before like the ones of (demi)liches, vampire lords,...
Party could go to raid the Stronghold with interesting fights.
Some Strongholds could be located in unworldly planes.

Trap books and trinkets

Given the book as gift, once opened, you're trapped in a plane. The book was meant to eliminate you by trapping in a maze. You have to find exit portal to a plane and find out who wants to eliminate you and why.