Hehe, Thulsa Doom was my first pretender in Dom2 Mp Games. The hopes I puted in him was as high as the number of afflictions he collected.
No, Dragon Mastery isn't a rip-off imho, it should be cool with some nations (Abysia, Jotun, maybe Caelum). But it can't be cast by Abysian or Caelian mages without empowerment.
But it's still possible do dedicate a pretender for summonong drakes (don't know ift's worth the invest).