Grollub ended up just being a big old beatstick. He didn't usually lead to as many interesting decisions as I had hoped, instead being subpar in the best of times.

I am replacing him with another lifegain payoff for black: Dreadhorde Invasion. Early testing shows it to be high risk high reward, with some cool synergies with sacrifice effects. It definitely warrants more testing.

Red and white can both support sacrifice synergies with their current card pool. Tokens in red can be fed to a cabal therapy or vicious offering, and white has recursion built in already to re-buy different things. I think I woudld like to include more sacrifice outlets, then, probably in black. Innocent Blood seems an interesting option, and would help control-type decks a touch as well. Unearth is also interesting, though I'm less enthused about bleeding the recursion into colors other than white. I'm not certain what spot either of these would take. Carnophage and Eternal Thirst are the likely spots for these, though I do like eternal thirst as both a lifegain enabler and removal build-around.

Also, let it be known that Sentinel Dispatch is on thin ice. It has been a staple of the cube since its inception, though its play patterns (namely: lack of actual decisions) are growing stale. I'm still looking for an interesting replacement. Lightning Core excavator seems interesting enough? Otherwise Ornithopter of Paradise would continue my colorless fixing theme, offering ramp to a deck that wants it and a colorless flying blocker to help nerf Herald of Torment and Vesperlark.