Right now I need to drop 7 cards and I don't know what my mana base should be. I'm also looking for suggestions of other cards to add.
15/47 cards cannot be played at instant speed. 8 of those cards have a net cost of 0 or 1. There are 16 creatures with the potential to "counter" a spell although some of them are fairly specific. If I cut Sakashima's and Standstill the deck will cost $40 less.