Elyessi
Would the magic classes be focused around healing, since he is a soul linker?
Hmmm most likely, though he can use magic offensively he just is terrible at it. That is why Chandra will eventually take over as he is...more likely to use offensive magic rather than defense.
Tak would originally just be offering helpful advice for those seeking to use magic, the different methods of tapping into magic and his philosophes about magic in general. It would be like the beginners guide to magic. Those who would end up becoming healers would possibly glean more from him, but otherwise he is going to have to pass the more offensive magic to his nephew XD