[Taqwus]

I don't think so. You're really supposed to use 'Call God' for that.

Ritual -- excludes undead except Mummies, excludes pretenders IIRC, turns unit into Mummy (exact choice depends on original unit size, which has funny effects for mounted units -- ex. dead heroic Black Hunter == Giant Mummy). Intrinsic special abilities are tied to the base unit and are therefore lost.