I got this idea from Pawn, in http://forums.spiralknights.com/en/node/52586

Currently we only have Lovepuppies, rock jellies, impostocubes, mewcats (and the now extict tortodrone)... But this is not enough! I would like to see OOO allow trojan, wolver, and other creature types have rare spawns as well. I am sure there are ideas in the works. I just want to show my support. :)

... As a side note: If bosses had rare spawns would that not be AWESOME? OOO would just have to be careful not to make these bosses the same as the Shadow Lair bosses. What if we could find these bosses in rare danger rooms?* (*insert evil laugh here)

(At this point, I am just randomly spitting out ideas... I just hope one of them gets implemented!!!)