Something interesting might be a thug-type that already has high MR, Ethereal, Luck, etc. but poor stats elsewhere, maybe barely above humans, for Astral. A "Great Astral Spirit", maybe?
As for Nature, I think maybe something fairly mundane, with high Attack and Defense, but low-ish (for a thug/SC) MR/maybe morale. "Beastman", maybe (you could steal the graphics from Pangaea)? It might even have an extra Misc slot to represent that it has a tail to put rings and such on.
Just throwing these out there.
