A few things for background
1. There are shadow lairs for all the normal bosses
2. The expansion pack is just the one level
Why not make a shadow lair for the expansion pack? It would be like the other ones but everybody has to have the expansion to do it. I don't know if you think it's a good idea but please give it a thought.
the idea is ok, it has only been posted a derpbillion times and increasing every week.