So here are some cards key to Ur-Dragon decks that will be competitive from Bracket 3 onwards
When she deals combat damage to a player, the player who controls her may pay two to return a creature card with three or less power from their graveyard to the battlefield, tapped
The text on Kaza, Roil Chaser reads: The next instant or sorcery spell you cast this turn costs X less to cast, where X is the number of Wizards you control as this ability resolves. In the same vein as Vadrik, you get the total cost of the spell plus kicker, and then reduce the total cost
It has a lot of powerful things it can do, and it can close games out in a very quick fashion
Being pretty simple and buffing up creatures, scavenge was decently well received when it came out
A lot of people think that you need to be a math genius to play Storm, and while it does help it's not a hard prerequisite