At first, I splashed in blue just for the Voidwalk, but it's not a cheap card and it's not immediately useful, so I cut the deck down to one. Two might be where I end up. I don't presently have anything to pitch cards to, so I am trying to tighten the deck up so I don't end up with useless copies of legendaries and what not.
The Far / Away work really well, and the deck being a sort of slow starter, I decided it would be cool to have some bounce to deal with aggro and other things in the meta that don't respond well to targeted black removal, thus the one Cyclonic Rift and a couple more in the sideboard. Pithing Needle seems pretty powerful in the current meta, so I tossed one in to see how it works. With all these utility cards making an appearance in my deck, I am seriously considering sticking a tutor back in. Traded out a Dark Prophecy for an Underworld Connections because two of the DP's might be a lethal mistake.
The only other thing I tossed in that I am not sure about is sideboarding Gainsay. I think I have the chops for the mirror match with Cyclonic Rift and enough other removal, but those one AEtherling esper decks seem brutal. I think having a couple of counterspells could really drop a turd in the esper soup.
The other thing I'm not sure about is Mutavault, in a deck that needs colored mana like this one does, it seems like Mutavault could really slow down getting out my two drop and three drop creatures. Is it worth it to mainboard, or is the sideboard good enough for these?