I've been hyping Whir Prison for good reason. The deck is really good. It's also really intricate, but not difficult.
You just have to learn all the tricks for all the matchups. Buckle up because here they are.
General Play Patterns
When you play Whir Prison, you aren't trying to win a game. You're just making them unable to win.
Your ways to do this are known from Turn 1. Every matchup can be reduced to a very small subset of cards that matter, and every route to you winning goes through handling that subset. You only have so many tools to do this.
There are few decisions about the cards in their hand, more about the cards in their library. Their plays only matter in how they might kill you before you shut off every card in their deck.
The five-second plan: Chalice of the Void their best cards, get Ensnaring Bridge, get Bottled Cloister to empty your hand, find the true hard lock against their two other cards that matter. Win on Turn 20 with Ipnu Rivulet recursion.
Now more details.
In every match, there are two degrees of lock you can assemble. There's a basic, urgent lock that prevents them from quickly winning the game, and then a more elaborate hard lock that gives them no outs over their entire library but takes more work.
Step one is always to assemble the urgent lock. Once there, if you can readily assemble the hard lock, you do that and the game ends. Often you can't, at which point your goal is to assemble one of your incremental engines that will find you the hard lock.
You have two cards that do this. Bottled Cloister draws you two cards a turn and always leaves you hellbent for Ensnaring Bridge on their turn, but sometimes Crucible of Worlds is otherwise important. With Crucible, you can leverage Tectonic Edge or Inventors' Fair to push ahead. Crucible of Worlds as an engine usually comes up in matchups where your hand size under Ensnaring Bridge is less of a concern and you can afford to not play lands you draw to keep churning value.
Winning the Game
You only technically have to know this in case someone pop quizzes you by continuing to play the game – much like the contents of Wuthering Heights in high school.
There are two-and-a-half ways to win with the maindeck configuration. Crucible of Worlds plus Ipnu Rivulet mills people. Academy Ruins plus Pyrite Spellbomb actually kills them, and Academy Ruins with Welding Jar or just casting a spell into a Chalice of the Void trigger effectively skips your draw step until they deck naturally.
All of these might involve you racing your own Bottled Cloister to win. Crucible of Worlds plus Ipnu Rivulet almost always does this, but you can do two draws to five cards milled/drawn math if needed. Academy Ruins plus Pyrite Spellbomb races if you have more than ten or so cards in deck, but if you are winning with Academy Ruins alone, you run out of cards in library if they have more than you.
So remember this trick: Engineered Explosives, sunburst to four. Welding Jar your Witchbane Orb, sacrifice Explosives, destroy Bottled Cloister. Back to one draw a turn, you can never deck with Academy Ruins, you win.
After sideboarding, you have a bunch of options and winning the game is easy. Sometimes you even accidentally win the game without setting up a full lock first!
All of these can win the game through Ensnaring Bridge in some way. Sai, Master Thopterist can win through Ensnaring Bridge if you just first attack and then play your drawn card each turn. Tezzeret the Seeker can set up Bottled Cloister and then ultimate once you hit five cards in hand on your turn.
Just remember to not accidentally Chalice of the Void-lock yourself out of win conditions, or to be ready to Engineered Explosives out your own Chalice if you do. This most commonly comes up with Tezzeret, Agent of Bolas playing against Shatterstorm.
The only card in the deck that requires dynamic decisions is Mishra's Bauble.
You don't have ways to shuffle for Mishra's Bauble, so target them for the info. In 42 matches I've had one game where I wanted to Ipnu Rivulet myself to clear a bad Bauble peek. Technically you could Tolaria West or Whir of Invention, but you are usually locked into casting the tutor and not waiting on your top card. Mishra's Bauble is just there to cost zero, be an artifact, and cycle when you don't need those.
If you're trying to keep a very low hand profile or are still trying to get to empty for Ensnaring Bridge, keep Bauble around. There's no need to accidentally draw running lands in the same turn if that would let 1/1s kill you.
The Matchup Guide
Whir Prison is so reactive to your opponent's deck that's there's nothing left to discuss besides the matchups.
Before I dive in, I must give a huge amount of credit to Michael Coyle, who streams as susurrus_mtg. He has an insane amount of experience with the deck, tons of great stream recordings to look over, and his own absurdly deep sideboard guide that goes through way more matchups than I could hope to cover in one article.
My plans are largely based off the current in-flux state of sideboards, where people haven't really decided what hate cards they want to show up with. I try to hedge against them all. In three weeks, once things settle down and the Prison deck adjusts a few cards in response, feel free to ask me what I'm doing, but don't forget to take a look at Prison Mike's stream first.
VS Izzet Phoenix
Izzet Phoenix doesn't have anything to stop Whir Prison. The best they can do is Izzet Charm you, or if they are really lucky Thought Scour and Surgical Extraction your Ensnaring Bridges. Any hand with a fast Chalice of the Void for one is brutal, as is any early Ensnaring Bridge.
Chalice of the Void: One immediately, two eventually
Ensnaring Bridge: Two cards in hand to start, zero or one to cover all marginal threats
I'm cutting the win conditions that don't provide extra value. Damping Sphere just isn't good because your other cards stop the spell-spam aspect of their deck better, and Engineered Explosives and Sorcerous Spyglass don't cover much.
Mono-Red Phoenix is very similar, but you have to worry about the one-cost, one-power threats more. Engineered Explosives is good. Getting stuck with cards in hand or letting them live to draw Shatterstorm is bad.
Your goal is to land Ensnaring Bridge and dump your hand as quickly as possible to stay above that line. From there, you need to Witchbane Orb to cover Conflagrate. You can Tormod's Crypt to buy a lot of time, and looping Crypt with Academy Ruins comes really close to a hard lock too. Inventors' Fair is the other way to slowly buffer your life total, but they are dredging fairly quickly. They can also just cast Creeping Chills from hand and Tectonic Edge won't cut off their fourth mana.
You're ahead in this race, but you just need to be very aware that is what's happening from the start.
Ensnaring Bridge: Zero cards
After sideboarding, your Chalice of the Void number changes to two to cover Ancient Grudge and Assassin's Trophy. If you have an extra Chalice, you can lock up one-drops to cover Nature's Claim first. Regardless, Chalice still tends to be a bit slow and something you don't want a ton of.
You also have another insane quick lock of Grafdigger's Cage plus any protection. This is technically beatable, but on a practical level they aren't winning if you Turn 1 Grafdigger's Cage into Welding Jar.
Spellskite as a blocker helps buffer your life total from early threats while protecting your Ensnaring Bridge from removal. Just having more of that effect is crucial to have both halves of Ancient Grudge covered. Note Spellskite can't stop Conflagrate if they just target it for one damage and you for the rest.
VS Grixis Death's Shadow
Stick an Ensnaring Bridge and you win. Stick an early Chalice of the Void for one and you win. If they make you discard or counter all your good cards you die, much like what sadly happened in my Grand Prix Los Angeles win-and-in.
I like Chalice of the Void for two as my answer to Hurkyl's Recall over Witchbane Orb, even if Orb hits Liliana of the Veil. The one leftover Sorcerous Spyglass is there for that planeswalker and random others like Jace, Vryn's Prodigy. I like Tezzeret, Agent of Bolas as more threats against discard heavy hands and random planeswalkers. I don't like Spellskite a ton, but it stops Temur Battle Rage and protects Sai, Master Thopterist.
My honest advice is to draw better than I did at LA, or at least have them draw worse. This matchup is good but losable.
The Humans matchup for Whir Prison is very similar to the Lantern Control versus Humans matchup a year ago, and is similarly close in a swingy way. If Ensnaring Bridge lands, you're a huge favorite. If Meddling Mage hits first and you can't Whir of Invention or Engineered Explosives past it, things get ugly. Once you lock the combat step, you just need to find some way to stop Noble Hierarch, which can even include sitting on Inventors' Fair lifegain.
One way they have to steal games even if you Bridge up is locking cards in your hand via Meddling Mage. I often like to set up my Engineered Explosives on two and just sit on it until I need to clear a Meddling Mage to stop this.
Know the Thalia, Guardian of Thraben versus Engineered Explosives interaction, especially with Chalice of the Void. Both X and the tax count for sunburst, but X is the converted mana cost. You can announce X=1, pay two total, get two sunburst counters, and then accidentally counter your own one-mana-cost card with your Chalice. Do it right.
The Urgent Lock: Ensnaring Bridge
Chalice of the Void: Get it out of hand and don't counter your own spells
Ensnaring Bridge: Zero cards
Torpor Orb turns their deck into Uno cards. All their sideboard removal for Ensnaring Bridge is disabled by it. Spellskite blocks Noble Hierarch and protects against Deputy of Detentions, and Sai, Master Thopterist just blocks in general. Tezzeret the Seeker is Ensnaring Bridge by a different name against Meddling Mage.
Their sideboard cards that matter are Gaddock Teeg; Kambal, Consul of Allocation; and sometimes Phyrexian Revoker. Teeg just reinforces the need for Engineered Explosives on two sitting around and is why Tezzeret, Agent of Bolas can't come in. Kambal is tricky, but if you already have the soft lock assembled you can eventually find an answer without casting many spells. Revoker is just another Meddling Mage that can name Engineered Explosives after it resolves, which only loosely helps them break out.
Bant Spirits is a much easier matchup. Your X-spells can dodge Spell Queller. Set up Engineered Explosives on three and Sorcerous Spyglass on Selfless Spirit to beat Deputy of Detentions. Sideboard more threats to hedge against Stony Silence.
VS Mono-Green Tron
Unlike Lantern Control, Whir Prison has a solid Mono-Green Tron matchup. There's an actual hard lock where you kill their lands and keep them from casting anything with Damping Sphere, not the soft draw step lock that folds to any card with Chromatic in the name.
Sorcerous Spyglass plays a key role letting you bridge your way up land drops with Damping Sphere. If you stop Oblivion Stone, they need seven mana to unlock with Karn Liberated. That's a huge amount of time to get the Crucible of Worlds / Tectonic Edge part going.
Chalice of the Void: One, slowing down their cantrips
Their current sideboard doesn't do anything scary to you, except maybe Thought-Knot Seer getting lucky and snagging a key card. Set up Chalice of the Void for one before trying to Tectonic Edge lock them due to Surgical Extraction. This might be one too many Ensnaring Bridges being cut, but I like having more room to kill them with Tezzeret 5/5s.
Witchbane Orb stops most of their deck. Easy, kinda.
You can win some games through Eidolon of the Great Revel, but usually it needs to die.
The Urgent Lock: Witchbane Orb, some answer to creatures
Chalice of the Void: One and two, just as fast as possible
Engineered Explosives: Whatever kills their relevant creature
Ensnaring Bridge: Zero
Cards that block, cards that gain life. The blocking is key and reduces the need for slower ways to work around creatures.
VS Frenzy Affinity
Ensnaring Bridge is good, but you need to rush to do more in this matchup. They will try to break through Ensnaring Bridge with Signal Pest, Galvanic Blast, Arcbound Ravager, and Cranial Plating. They will present the ones they draw quickly.
Just go through and shut those threats down as they force you to do so in whatever way you can. You have Chalice of the Void on one or two, creature removal, and Sorcerous Spyglass to fight back. Engineered Explosives plus Academy Ruins is also a soft lock.
You do have a long-game hard lock that shuts off those four outs, though, so you can beat a resolved Experimental Frenzy.
Chalice of the Void: One and two
Engineered Explosives: Zero, one, or two
Ensnaring Bridge: Zero cards
The last three cuts are my interpretation of "shave random cards." Chalice of the Void cutting off your own cards is honestly annoying, especially when you're bringing in two-drops but want to stop Ancient Grudge. Whir of Invention is slow in multiples and nothing you find solves everything the way it does in other matchups.
I might be short a Spellskite on the way in. It stops modular and removal, but not blocking isn't great for two-drops.
I covered tricks for the Amulet Titan and Mono-Red Prison matchups last week.
The Whir Prison mirror Game 1 comes down to decking and everything being locked out by Sorcerous Spyglass. Don't cast Bottled Cloister and get in your Ipnu Rivulet and Academy Ruins while you can. You also don't have to select a card with Ancient Stirrings, or even cast it. Post-sideboard, people die to the threats at random, so don't punt the more skillful game.
Cryptic Command control decks are terrible matchups. Game 1 is hard to steal and involves Crucible of Worlds really quickly and Sorcerous Spyglass on their planeswalkers and probably Chalice of the Void for four. Then you sideboard in threats and hope they work.
Ad Nauseam might have Echoing Truth Game 1, so attack their combo pieces. Chalice of the Void for three is the long-term hard lock, but one shuts off Angel's Grace and lets Engineered Explosives cover Phyrexian Unlife. You can Sorcerous Spyglass Lightning Storm and Pyrite Spellbomb Laboratory Maniac if they have no tricks.
Storm has one Repeal Game 1. Chalice of the Void on one and two stops them, just know you have to cast Chalice one before Chalice two or you counter your own Chalice. Spellskite also doesn't stop Repeal or Wipe Away.
Yes, Whir Prison will get worse once everyone has their hate lined up, but that has happened to every artifact deck ever. You have tons of tutors and a whole format to sift though.
I'm not an expert on the entire list of options for Whir Prison, but I have some suggestions. Tezzeret the Seeker and the last Spellskites are the current negotiable cards in the sideboard. Jester's Cap I've been told is good to help against combo and to cover "eventual" Shatterstorms or tutor targets. I like Dominic Harvey's Unmoored Egos in a similar vein if you want more copies past the tutorable first Cap.
As long as the Faithless Looting decks remain at the top of the metagame, Whir Prison will be a real threat. Maybe one week everyone has too many Shatterstorms for your tastes, but give it time. When you need to learn the deck, there is now even more material out there to copy all the tricks from.