Ultimately I think the deck's primary issue is one of sequencing. You have to have early enablers for the synergies of the deck and early creatures to apply aggression, but since those creatures also serve to recur Vengevine, you're incentivized to hold them until they can serve that purpose, thus blunting their effectiveness as aggressive elements. And should you decide to play them as early as possible, the deck doesn't contain a high enough density of creatures to put future Vengevines to good use.
Upon this realization, you have two options: either move further toward a Hollow One deck or further toward a Vengevine deck. Today's list takes the former option, refusing to eat its vegetables. With that understanding, the most important change in the deck is supplementing Faithless Looting with Burning Inquiry, which is both cheaper than Cathartic Reunion and better at enabling Hollow One.
The consequence of this change is that you need a high density of cards you want to discard, since Burning Inquiry does not give you an option. This deck achieves that with several heady additions. Bloodghast and Fiery Temper are pretty easy finds and deserving inclusions, but Flamewake Phoenix and Call to the Netherworld are more obscure and quite important.
Flamewake Phoenix is easily recurred with Hollow One or Gurmag Angler. Although its dependence on another card means you only want a few, the added density of graveyard-centric threats makes it notable. Call to the Netherworld gives you some degree of control over Burning Inquiry by recurring a discarded Street Wraith or Gurmag Angler. Returning a Wraith off a Faithless Looting can notably bring you to the magic third discard to make Hollow One free.
Finally, this additional discard capacity lets you play Flameblade Adept as the one-drop of choice, creating a clear desired sequence: turn 1 Flameblade Adept into turn 2 Faithless Looting / Burning Inquiry, play a land to recur any Bloodghasts, cast any Hollow Ones and recur any Flamewake Phoenixes with the other mana, and you've effectively leveraged all your resources to their utmost.
This list sacrifices very little in terms of explosive power over the R/G list and gains a lot in consistency and ease of sequencing, which should go a long way toward shoring up the shell's weaknesses.
- 1 Bomat Courier
- 4 Hollow One
- 4 Bloodghast
- 4 Flameblade Adept
- 2 Flamewake Phoenix
- 3 Gurmag Angler
- 4 Street Wraith