I think you can type in any monster type that exists in the game, nataraja, doom horror, priestess, dragon, militia, vaetti lord and troll archer should all be working targets. I haven't tested this, but in SunrayBe's site (
www.freewebs.com/dominions2) there is a list of wishes and I think it listed those. You will get them as units, not as commanders, and although you can cast Gift of Reason to make them commanders they might or might not have the magics they should. I think pretenders have their magics, but am not sure about general mages.