This next spoiler happens to be the first dragon introduced in the Innistrad Block:
Limited bomb on the level of Reaper from the Abyss. I mean, this dragon can just end the game if it ever has the chance to attack if your opponent doesn't have an answer for it (and maybe even before then if you have enough mana to activate its ability the moment he enters play). In the greater Legacy scheme of things, I'm not sure how well it stacks up in the dragon hierarchy of Magic past and present. It's a 6cc dragon so it already has some stiff competition. And honestly, when you start getting into that 5cc, 6cc, or 7cc+ range of fatty creatures, I want a little more bang for my buck when it comes to card advantage. I want something like Bladewin the Risen that has a plan B and C when it comes to potential responses from your opponent. While Mooveil Dragon just kind of sits there and just is. Because of this, I don't think it's going to see much play outside of limited and budget casual.
I don't really have anything specific to go for on this one. Obivously the Moonveil Dragon wants to pump as many dudes as possible to get maximum value. So I say just go red/white, throw in some solider tokens and just go to town. This one isn't too exciting when deck construction is concerned.