I think it’s fun with some variation in the game, and I always felt levers would be a natural part of any dungeon puzzle. So here’s my suggestion:

1. Special room: Draw bridge. You have to find the lever in the dungeon to lower the bridge. Graphics can just be a simple one tile part, same graphics as the wooden pathways already found on certain floors. This shouldn’t require more balancing as it’s similar to a locked room needing a key. But to make it more challenging, make the drawbridge only last X turns, so you better make haste. You can bypass the bridge using Levitation, just like trap rooms.

2. Lever puzzle room. Three levers, in a room with lots of traps. Wrong lever trigger every trap in the room, such as summoning, poison darts or similar. Either find a page containing a (answer/clue/riddle?) somewhere on the floor, or take your chances with pulling the levers.