Unseen Tempo

Seems a little weak on interaction with just a set of slay and annihilate. I would throw in crests, shadow waystones, drop the favors for either permafrosts or winter's grasps (nightfall decks need fixing a little less than most 3F decks do), and drop the spellshield architects and bloodletters to mix in strategizes/unseals/daring pioneers. They would wind up being a dead draw when the darkveil agents are up and you're far better protecting them then throwing another aegis generator in.

It might be a good idea to try swapping Bisma for Unseen Commando, which should have more immediate board presence (though I do like the haunting scream + Bisma combo)