A cube built from cards set on Ravnica. I do have a special rule for the cube which is that a card is allowed to appear in it equal to the numbers of times it has appeared in a Ravnica set. Therefore you get additional fixing with 3 of each shock and cards that really push a guilds theme or playstyle like Skyknight Legionnare in boros or Wee Dragonauts can show up extra times. It's been drafted in various forms multiple times but I can't claim to know how balanced each color pair is but everyone that I've had play it has had a good time so I'd call that a win.