What about making a module of Caverns Of Chaos, where the players get to play as monsters? It's Chaos after all, isn't it? Why would their forms be limited to change into dwarf, elf and human only? And at the nightmarish modules, instead of having a chance to play with legendary characters, you could get to play with big figure monsters. I bet that would be really fun and it would also help new players get familiar with different monster types and discover new card synergies and strategies. It wouldn't be that hard to code, would it?