Time is a bear; it's been hurry hurry all week so when rushing out the door to play games with Matt, Caitlin and Noah I went with the following swap:
-1 Blightsteel Colossus
-3 Maelstrom Archangel
1 Lay of the Land
1 Channel the Suns
2 Razia's Purification
I became a big fan of Razia's Purification in multiplayer, I'll tell you that much. In a four player game, I was able to cast an Eldrazi, follow it up with an attack, then the Purification and...nobody had anything else left to play.
In duel though, I'm pretty sure the Purification won't really save me when I need it too. I am interested in the card because it's a way to break the game-annihilator mechanic + Razia's Purification means that I will win, no matter what. I'm fairly certain, however, that this just means I will win more. That means The Glory of Cool Things rule is in effect and that should almost always be avoided.
I like the notion I have with Lay of the Land and Channel the Suns, but I don't think it's quite right. Channel might be correct: turn three Fist of Suns, turn four Channel said Suns does help jumpstart Overkill. That might be the best notion, as there is a huge difference between getting Kozilek out on turn four versus five.
I'm still searching for a catchall though and I'm even tempted by Wave of Vitriol. In Garruk's Wake, Decree of Pain or Plague Wind are probably my best choices though.