Good looking deck with a very cool aim but i have some suggestions:
Wall of Denial
I know it doesnt keep to your colour scheme (Blue,White) But is a great all rounder wall
Creature controll at its finest.. for when the walls come down.Also acts as a constant threat of wiping the board.. buying you turns.
Seems crazy not to run a black deck with dark depths and not this card.
Cheap defender which people dont like coming up against because of Deathtouch. Makes for a tidy turn gainer.
I try to run these in any deck I have with green..Thinning your deck of mana to pull combo cards just makes sense..bonus is snow covered counts as basic land.
Just noticed you only had one Dark Depths.
So you can find it in a pinch.