With the existence of the Corrupted Overlord, I can't help but wonder if one can build a group that takes full advantage of its theme.
I would say no, unfortunately. Trying to run Mirefolk cross faction would be an exercise in frustration. If you did want to base a deck around him (which imo he's not worth doing), you'd be better off ignoring the fact he's a mirefolk and just make a goodstuff fs/ud, or maybe a fire deck - not sure how much support FS can offer to fire beyond sixul though.
Run him in a split UD/SL mutant deck. Get The Farm Relic and have fun. You can also have a fun fire damage subtheme.
Abandoned, and taking your advice. Wish I still had my Mutated Drake. That being said.. Having a Soulbleeder with Blood Stained claws, backed up by 2 mutant doctors and receiving horrific mutation after horrific mutation is.. solid.