In this three color build where mana is already an issue, I prefer Book of Rass to Greed, but you could run both
Voldaren Bloodcaster Summoner
This means that if an opponent wants to play a land, they'll have to ensure that there aren't enough for Impending Disaster to trigger
Once you take this action, you may cast that card if it's legal to do so before any other player can take actions
Eventually, someone realized that Monastery Swiftspear was contributing enough wins to the Death's Shadow deck and asked, "What if we just cut all that other stuff?" Cue the appearance of "Death's Shadow Blue," or UR Prowess
(10/1/2009) In a sanctioned event, a card that's "outside the game" is one that's in your sideboard