i don't really know the best color combinations for tribal dragons, so I'm having trouble finding the right general. I was thinking jund, so {karthus tyrant of jund} or prosh.
{Scion, the Ur Dragon}. Hands down. Tutor into Reanimator, also a bit of a toolbox. Just a little nasty in the mana see department.
Check my "when your powers combine" list