I think you probably want to add some of the cheap sweepers. The deck very obviously has some incredible haymakers in the late game, but I'm not seeing too many ways of ensuring that you get to the late game. You've got targeted removal and counterspells which are undoubtedly fantastic, but a list like this that is intentionally trying to funnel all of its early game resources into getting to the late game usually arrives at the late game at a massive disadvantage. The solution: boardwipe. Judging by the size of your creatures, something as classic as [[pyroclasm]] could wipe out mana dorks in the early game or decimate a token board in the mid game without killing your own guys, or you could go with the generally better [[firespout]] so long as you're careful about when you play your commanders. In a similar vein, I'm surprised there's no [[blasphemous act]]? Sure, it would kill your own creatures, but I feel like you'd be fine sacrificing a vial smasher to wipe your opponents board and do 9 damage to their face.
In sum, I'd recommend looking at your late game haymakers and decide on 2–3 that don't quite excite you as much and replace them with cheap sweepers to slow your opponents down.