I realize that
Spell Queller would fit right at home in this deck, but I want to keep it UR for consistency and for budget reasons. Also, adding white to the deck opens up so many options that I feel like the deck could lose focus.
Dimensional Infiltrator Might be a tad out of place as it isn't a spirit, but it is a 2/1 flash flyer and I'm not sure what else would fit the bill.
I really want to include Essence Flux, I'm just not sure what to put it in for. It could replace Turn Aside in the SB. The only real advantage I see with turn aside is that it can prevent Fevered Visions from being removed.
Exquisite Firecraft vs. Collective Defiance is something to consider. I think that Collective Defiance is better because of it's versatility and the fact that it can both burn face and remove troublesome things like Kalitas or Gisela, however in Blue.x control matchups the uncounterable ability of Firecraft could obviously be important.
Brutal Expulsion is a somewhat random inclusion, though it's versatility is a bonus and it gives us some hedge against planeswalkers. I think it fits the deck fairly well, but there may be better, lower CMC options.
There are also some other top end options for Niblis of Frost. I just began testing with this, and it seems rather good as it synergizes with the other spirits and while there are not a whole lot of instants/sorceries in the deck, even just tapping down something for a turn or two can be enough. The other options for this slot are Goldnight Castigator or Akoum Firebird
Lastly, the sideboard is kind of up for grabs. I brought in more removal, as well as Turn Aside which seems like it can be pretty good, although maybe Negate is just better. I could also see Seismic Rupture being put in the SB.
