If you’re familiar with the red prison decks that have continued to increase in popularity in Legacy, then you’ll recognize the game plan of this Modern version. These decks look to accelerate out some lock pieces (some soft locks, some hard locks) to make it so the opponent can’t win. This lets the red deck take its sweet time to win the game. But cards like Ancient Tomb, City of Traitors, and Chrome Mox aren’t legal in Modern like they are in Legacy, so you’re going to have to improvise.
The key piece of interaction in this deck is Chalice of the Void. Chalice on 1 shuts down a number of decks entirely and it’s a huge nuisance to many others. Getting a Chalice down on 2 can also be excellent, but you’re usually looking for a Chalice for 1 on turn 1. You don’t have a single card in your deck that costs 1 mana, so this does nothing to disrupt your own game plan.
While Chalice is one way to shut down your opponent’s spells, ensuring that their lands no longer function is another reliable approach. Blood Moon is one of the most frustrating cards in Modern to play against. Preventing lands from tapping for the correct mana while stopping players from assembling Tron or Valakut triggers makes Blood Moon an excellent weapon. A turn-1 Blood Moon can make sure that your opponent never has access to non-red mana throughout the game, and turn 2 is often more than enough to slow them down.
These lock pieces are great for stopping many of Modern’s best spells, but sometimes you’re on the draw, your hand isn’t great, or your lock pieces don’t interact with your opponent very well. Ensnaring Bridge is your next line of defense to make sure you stay alive. You’re already using fast mana to accelerate out your lock pieces, even when it means you’re taking serious card disadvantage. Ensnaring Bridge rewards you for having a smaller hand size and then keeping it empty.
For when Ensnaring Bridge isn’t enough, you have some solid removal spells. Abrade can take down a creature or one of Modern’s many strong artifacts. Anger of the Gods and Slagstorm provide you with a couple of sweepers for when you fall behind while trying to set up your lock.
Your best removal spell and your best finisher is Chandra, Torch of Defiance. You’re playing all four copies, as this is one of the best threats you could hope for. You also have tons of ways to accelerate Chandra onto the battlefield, and she’s a 5-loyalty planeswalker that ultimates to win the game or kill a relatively large creature immediately. Chandra is mana, card advantage, removal, and a win condition all rolled into a 4-mana package.
You have quite a bit of fast mana at your disposal. First, you have Gemstone Caverns to steal the play when you would otherwise be on the draw. This gets you up to 2 mana immediately to deploy a turn-1 Chalice or use other fast mana to accelerate out yet more threats. You have Simian Spirit Guide to give you an extra mana early (or a 2/2 attacking “threat” late), and you have five Rituals. You’re playing 4 copies of Desperate Ritual as you can occasionally splice one onto the other and turn your 4 mana into 7, and it’s otherwise functionally identical to Pyretic Ritual. These only accelerate you by a single mana, but that’s all you need. You want to empty your hand and cast fast Chalices, Bridges, Moons, and Chandras.
The other threats you’re looking to get out early start with Goblin Rabblemaster. While you can usually sit behind Blood Moon, Chalice, and Bridge to win the game at a leisurely pace, that isn’t always the case. There are combo decks or control decks that can get out from behind these powerful pieces. Goblin Rabblemaster is a quick clock that will end the game in a hurry if left unchecked. The tokens can also conveniently attack under an Ensnaring Bridge each turn before you play your card in hand.
Pia and Kiran Nalaar is yet another weapon that can provide multiple aerial blockers and attackers. Sacrificing your own Chalices/Bridges for damage and to free up your own spells and attackers can win the game. Hazoret the Fervent and Glorybringer provide some big haste threats that play well against the Lightning Bolt and Fatal Push removal suites of Modern. We know these creatures well from the Mono-Red decks in Standard and it turns out they’re still sick in Modern, especially if you can accelerate them out a couple turns early!
Mono-Red Prison has been emerging as one of the best decks in Legacy. While there aren’t quite as many tools in Modern, you don’t have to worry about Force of Will!