I'm not so big on the split cards anymore. Also, Flayer seems like a strong card that can give G/B a good identity outside of the dredge deck. Probably would help Jund too.
F Miscreant is a little cute compared to a cube that is defined by Dredge and Pyro. So here's delver of secrets. Is this just becoming a legacy cube at this point? Yeah maybe.
Helix was a little too powerful in the way it combined the life gain and burn archetypes. Instead, here's Figure of Destiny. Toralf did basically nothing and is getting cut for a beater. Flame Burst and Kindle are identical, so we're going to cut Kindle for a new red 2-drop, I think Earthshaker Khenra fits.
Tymaret bridges the gy and scry ideas (if we even need/want to) and also I think adds more to the dredge deck (which we should probably cut a piece from here soon . . . .)