This deck uses Tortured Existence to loop Bartered Cow and make a bunch of food tokens. The win condition involves using Glaze Fiend to swing in with a flying beater, as well as the usual tortex wincon of grinding your opponent out of resources and winning with Crypt Rats loops. The list is mostly teched to beat aggro decks, as that's what I play against the most in my local playgroup.
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Listed below are my thoughts from the beginning of my experience playing tortex. There is some insight here, but I'm mostly keeping it here to see how much I've improved since then.
This version of Tortex uses the Golgari Brownscale plus Grave Scrabbler plus Spore Frog engine. On your turn: dredge Brownscale, pitch it to get Scrabbler, then pitch Scrabbler to get the Frog and one combo piece of your choice. Play the frog, sacrifice it if you need to, then repeat for the next turn. The full engine takes B,B,B1,G mana, so don't dredge aggressively until you have enough mana for the lock.
Once you have the combo assembled, if you have a Spoils of the Vault you can pretty much insta-kill, but there's no reliable way to recur it if you mill over it. Without a spoils, just spend your excess black mana each turn to trade a Bartered Cow in your hand for a cow in the graveyard and swing with your beater. It's a very slow combo, but you're resilient to non-exile removal. If enough of your graveyard gets exiled there's basically nothing you can do, so just stall with spore frog until the opponent gets bored and concedes or you dredge yourself into oblivion.
The utility pieces I've included are: Sakura-Tribe Elder, Tilling Treefolk, and Krosan Tusker for lands and card draw; Crypt Rats for a board wipe or face damage in a pinch; Stinkweed Imp to fill the yard quickly if needed; a single Rancor to get around chumps; Rofellos's Gift to get back Tortex and Rancor; and Commune with the Gods and Winding Way to filter your draws.
Cards I'm considering for the list: Carrion Feeder or Viscera Seer to sacrifice Scrabbler, Caustic Caterpillar for the sideboard; might put Songs of the Damned back in, because it's really fun, but it did nothing most games.
EDIT: 7 Oct 2019: Cut Red from the list entirely. Atog and Disciple of the Vault messed up the mana too much to be worth the effort. I think going all in on Glaze Fiend is fine, especially since there are no Surgical Extraction effects in Pauper currently.
EDIT: 18 Nov 2019: Been playing with the list for a few weeks now. Cut some chaff like two Rofellos's Gift, Songs of the Damned, and Myr Servitor; fixed the lands; and tightened the sideboard a bit. Still not quite done with it; need to playtest versus more matchups.
EDIT: 18 Jun 2020: Haven't changed this list in a while, but with the downshifting of Cauldron Familiar in Jump-start, we have access to a new powerful combo. I cleaned up a little bit of nonsense in Rofellos's Gift and added in Benefaction of Rhonas which is a solid card I've been contemplating for a while.
EDIT: 23 Sep 2020: Cleaning up the list a little, and adding the thriving lands in, even though I don't have them in paper yet.
EDIT: 11 Nov 2021: More tidying up. +1 Cat, +1 Blight Priest, +1 Carrion Feeder -2 Glaze Fiend, -1 HorrorOTBL. Kinda wanna add another land or another steve, but not sure what to cut, maybe the Blight Priest.
