So, here’s my idea:
The players are given a magical device that allows them to shift, as a standard action, between the planes. Any one of the heroes can do this on their turn, and it’s only between the Feywild, Material Plane and the Shadowfell. The players are linked together, and so they can’t switch to another plane without everyone going. This dungeon exists on all three parallel planes of existance. As such, the players can step into the other planes in order to get past particular barriers. The dungeon is worn down in the Shadowfell, normal in the Material Plane, and overgrown in the Feywild.
As the players move through the dungeon, they must figure out which plane to shift to in order to get past a particular barrier. Perhaps, in the Shadowfell and the Material plane, a room has a massive chasm in the middle of it. In the Feywild, however, there is a long, vine covered rope bridge. As they cross it, they are attacked by monsters. They can’t shift, or everyone falls and dies.
In another room, the players need to shift to the Shadowfell for some reason (perhaps the text on the wall can only be read in that plane). When they shift, it turns out the room has lots of sinkholes, and some of the players start to fall. If they try to shift back while a player in a hole, the person will be encased in stone when they return to the Material plane.
I’m not sure how all the levels would work, but you could have each room as a set of three pictures on your iPad. You use the iPad as the battlemap, placing your figures on it.. As you shift, the DM swipes his finger on the board, and the room changes beneath the PCs’ feet.
I think it could be really cool, if implemented right. What do you think?