We have Shrapnel Blast? I didn't know that. I thought we had Galvanic Blast only...
You want 3 Everflowing Chalices in the deck too and more than just the 1 Collar as there will be artifact removal. Liquidmetal Coating is too bad to be here and you should have something like Sphinx of the Jwar Isle as an additional finisher.
I'm guessing Last Word but with cantrip. Seems good to me and makes perfect sense to me as it fits into the Grixis deck for Extended he mentioned in his article.
A 1 of Gigantomancer might work. Fetch it with Fauna Shaman. Some toolbox options don't hurt too much. And notbites thanks for explaining regeneration to Beau.
@Beau check out Noel's article. He also includes Nantuko Shade and Pestilence Demon because you can use Shade's and Demon's ability just like you can use Molten-Tail Masticore's abilities.
First of all, Thought Gorger is four mana and so usually by turn 4 you still haven't played out everything you need and so discarding your hand isn't a great idea. Casting it later makes it less impressive, when compared to 2 or 3 Vengevines you could be reviving. Second of all it clogs up the 4 mana slots, which are already quite packed and it detracts away from your plan of bringing back Vengevines. Third of all you aren't guaranteed to have a refilled hand as infect+proliferate may feature in the format and don't forget about Vampire Hexmage.
Take out the Renegade Doppelgangers. They were good when copying an extractor demon, on turn 3, but only being able to copy a vengevine at best isn't going to win you a game.
Copying a Vengevine is great already but being able to copy Molten-Tail Masticore, Necrotic Ooze or Fauna Shaman makes it exceptional.
Seems like a fun start. It sucks we loose things like Merfolk Looters to accelerate the the pitch engine. I like the fact that the Ooze will get the Masticore ability, but I'm still not enjoying the cost of 4 and removing a creature. But all things considered, a solid decklist, balanced choices, and a decent start to be worked with and retooled.
You've got useless creatures in your graveyard to remove sometimes which have been milled by Hedron Crab or killed by mass removal. Get rid of those Doppelgangers, Cryptologists and Hedron Crabs that are doing nothing. Perfect.
Hedron Crab helps you mill things into your graveyard and also helps with bringing back your Vengevines. I considered Geth, but it's too slow. The point of the deck is to win fast.
Also, while I respect your Johnnian principles in having no non-creature spells, I would suggest Training Grounds. That card is absolutely insane with Molten-Tail.
EDIT: And Drana. And Geth.
Training Grounds with Molten-Tail is absolutely insane and overkill. I'd rather have more creatures to fuel Vengevine for beatdown. Drana is too slow too.
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You want 3 Everflowing Chalices in the deck too and more than just the 1 Collar as there will be artifact removal. Liquidmetal Coating is too bad to be here and you should have something like Sphinx of the Jwar Isle as an additional finisher.
Extractor Demon was a big loss. Hopefully Molten-Tail Masticore is a good enough replacement.
@Beau check out Noel's article. He also includes Nantuko Shade and Pestilence Demon because you can use Shade's and Demon's ability just like you can use Molten-Tail Masticore's abilities.
Copying a Vengevine is great already but being able to copy Molten-Tail Masticore, Necrotic Ooze or Fauna Shaman makes it exceptional.
Thought Gorger isn't any good here. It doesn't help you achieve what you want, which is attacking down with a lot of threats really quick.
Pestilence Demon is an interesting 1 of. Maybe from the sideboard?
You've got useless creatures in your graveyard to remove sometimes which have been milled by Hedron Crab or killed by mass removal. Get rid of those Doppelgangers, Cryptologists and Hedron Crabs that are doing nothing. Perfect.
Hedron Crab helps you mill things into your graveyard and also helps with bringing back your Vengevines. I considered Geth, but it's too slow. The point of the deck is to win fast.
Training Grounds with Molten-Tail is absolutely insane and overkill. I'd rather have more creatures to fuel Vengevine for beatdown. Drana is too slow too.