Lets talk about a midrange deck that is built around Rottenmouth Viper. I have been trying multiple different builds trying to get to a deck that can win without Viper but still works towards a backbreaking Viper. The deck has a balance of removal and hand disruption to stabilize against a lot of the meta until we can reach a point where a Viper can close out the game.
ORIGINAL DECK LIST
MAIN DECK
Creature Breakdown
Gilded Goose and Prosperous Innkeeper: This little guys help ramp us to the late game, while adding two things to the board.
Bloodtithe Harvester: A strong two drop that provides an ability to loot, could remove small creatures, or paired with Fable can take over game by removing every threat your opponent has.
Woe Strider: Woe creatures two creatures, while also lets us sacrifice creatures to help us dig for the Viper.
Rottenmouth Viper: A powerful 6 drop that can have it's casting cost discounted if we sacrificed nonland permanents. When it enters or attacks it gains a counter and then has the ability to punish your opponent for each counter on it. Most of the time they will be forced to discard the removal they had for Viper just to stay alive.
Noncreature Breakdown
Removal Suite: 4 copies of Fatal Push, 3 copies of Bitter Triumph, and 1 Blot Out to answer the opponent's threats.
Bitter Reunion: Setup piece that draws into more removal and into our viper.
Fable of the Mirror-Breaker: 4 copies of this dominate card that helps loot away cards that aren't good in a matchup, while also creating a 2/2 goblin that creates treasures to help enable revolt or to cast the Viper. Later it can make copies of the Viper or Harvester.
Treacherous Blessing: Enters and draws 3 cards. Later we can sacrifice it to the viper.
ADJUSTED DECK LIST
MAIN DECK
Creature Adjustments
Voldaren Epicure: Cut the green creatures to make the mana more consistent. Voldaren still adds two permanents to the battlefield, while also powering up bloodtithe.
Kroxa, Titan of Death's Hunger: Add one copy of Kroxa to give the deck an alternative way to win the game.
Noncreature Adjustments
Discard: Add 4 copies of Thoughtseize and Hopeless Nightmare for turn one hand disruption.
Removal Suite: Add 1 copy of Tithing Blade and 2 copies of Nowhere to Run, since they can remove a threat, while also being a permanent to sacrifice.
Sideboard Breakdown
Bitter Triumph: It is a cheap removal spell that answer a Planeswalker.
Heartless Act: Removal spell that helps against aggro and can provide a win against a Arcfiend of the Dross.
Unlicensed Hearse: Graveyard hate to help against Phoenix or Greasefang.
Duress: Away to disrupt our opponent's combo or to remove counters or removal spells.
Go Blank: Additional hand disruption that also exiles their graveyard.
Ob Nixilis, the Adversary: Helps against control and other grindy matchups.
Withering Torment: Removal spell that can answer problematic enchantments.
Extinction Event: Few copies of this exile based sweeper that can help stabilize against aggro, mono green devotion, or deal with slasher for good.
Jegantha, the Wellspring: Sweet companion.
Sideboard Guide
Rakdos Prowess
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Azorius Control
Izzet Phoenix
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Jund Sacrifice
Enigmatic Fires
Next we will cover non tier one decks that you might face.