Judging by your terminology, it sounds like your campaign is DnD (or generic 'high-fantasy') heavy.
There are no clerics or wizards in the Conan RPG. All spellcasters are covered with the character class Scholar, which is an marvelous and extremely flexible class (although hotly debated by a few board members here). Magic is called sorcery and is, for the most part, exceedingly evil.
The idea behind your term 'tiefling' is remarkable, 'though I don't think I've encountered the word in REH's Conan saga.