Since The Ur-Dragon has massive stats, you'll generally want to be attacking with it, however
These sets are either very strong multicolor sets (Invasion/Planeshift, Khans of Tarkir, Return to Ravnica/Gatecrash, Shadowmoor), sets with great removal at common/uncommon (M11, Conspiracy/Conspiracy: Take the Crown) or strong colorless or colored cards that can reward any draft (Mirrodin/Darksteel and Theros)
It could do with High Market, thougha great sacrifice outlet to include
The Kicker ability helps this cause, though paying eight mana isnt always easy
Notable cards in this deck include Ranar the Ever-Watchful , which drives the main synergy, Cosima, God of the Voyage, for card advantage, and Glorious Protector , which offers versatile flicker effects