To return to the normal realm the party will have to break the seal on the magical gateway. This can be done a number of ways:
- The sigil under the crumbling ground, forcing open the portal with magic
- Creating an alternate portal
- Finding another way to fracture the barrier.
If the evil wizard dies, the link to the prime material plan will be broken and the party will have to find another way to bridge the gap between the pocket universe they are in and the real world.