even with the increased land count suggested above, your mana-curve is waaay too high
I've got a few extra bits and pieces to deal with organization, bulk, and color coding in my setup as well (more on that below), but if you're starting out as cheap as you can, you only really need the first two items on this list
Incapsula incident ID: 562000120617139272-1510509984808567605
Moonsnare Specialist: This ninja makes combat especially tricky for your opponent, and its effect is still pretty good even if you cast it normally
But most often, the negativity around powerful cards or decks has more to do with how they reduce the sense of identity or ownership around a deck, like we just examined
Sephiroth on the other hand plays into the usual control strategies favored by Blue/Black by growing in strength for every opposing creature you remove from play