Via Beatrice, you can bin over the course of a turn cycle, a handtrap of your choice (Ive chosen Droll & Gamma) and Link into the VRAINs!, necessitating only a way to pop your own card
City of Ass is a parody of City of Brass
Flicker it to draw more cards with Flickerwisp
Although it fits a nice spot on the curve, you dont need to play it on turn three against the red removal decks, and instead can wait until Ajani, Adversary of Tyrants or Lyra Dawnbringer can help it survive those removal spells when youre not under too much pressure
If you cast it without a Time Vault, you could go find it and threaten to take infinite turns, next turn
Despite being reprinted in Commander Masters, The Ur-Dragon surged in price following the release of Tarkir: Dragonstorm