Ok, /tg/, I'm making a giant tower to house the final boss for my dnd3.5 campaign. the tower is mostly made of iron beams and stone, with very little wood, although it is shaped like a super-tall octagonal pointy-roofed guard tower. The top two floors have been reserved for the final boss battle with undead/secrets god Vecna which has already been planned out.

I need a bunch of rooms below him in the tower. There's at least 5 floors I need to flesh out with either obstacles, guards, puzzles, or flavor-based rooms (storage room, laboratory, etc...) and the rooms can't be larger than 100'x100' I'm just running out of ideas so I sought your sage advice. 'you' being the internet.