Undead consuming peasants is a cool idea. Should have something mechanic-based to supplement their birthrate though, like having all units killed in...
Maybe run a survey and see if they have CS or WT's. I've never had any issues with infiltrate, but then again I havent done anything other than Rogue...
How about using peasants instead of runes for spells as well? Like human sacrifices. Each peasant amounting to maybe 10 or 15 runes. Also the option...