I haven't been this excited about a deck since Underworld Breach.

Origins

A week ago, Italian Legacy grinder TrueHero tweeted a 5-0 with a take on Doomsday that made my brain explode.

Traditionally, "slow" Doomsday lists leverage cards like Baleful Strix in order to stall the game and generate card advantage while finding / clearing the way for the Doomsday combo. TrueHero's list went a step further: it used Murktide Regent to give the fair plan some real wings, so to speak. As another card to bridge both the fair and unfair game plans, he included a pair of Temporal Mastery, since while Time Walks function nicely as a way to cycle through a Doomsday pile, they also excel at turning a Murktide Regent into a very lethal threat.

Initial Tuning + Grixis Tempo Doomsday

As excited as I was, I had a few issues with TrueHero's initial list: The Street Wraiths (aside from churning through the Doomsday pile) didn't do much outside of hurt your life total. With no Lotus Petals or Lion's Eye Diamond, the corner-case benefit of Street Wraith, which is to cast Doomsday with UU left over, have Street Wraith in hand, and cycle into Thassa's Oracle (as long as you have enough devotion to make up for the fact that your library isn't empty), didn't seem worth it to me.

Also, the 3-drop slot was oversaturated, and Sedgemoor Witch, which is a cool card in theory, doesn't fly. Since Ragavan's ban, the entire Delver threatbase flies, so I didn't like accelerating into a 3-drop that's supposed to stabilize your board but essentially has "can't block" written on the card.

At the time I saw the list, I was extremely high on the card Pyroblast. Between Delver, Daybreacher, and even Doomsday, Pyroblast has a ton of value across the board, and blue decks have never been more susceptible to the card. I wanted to play 4-6 copies in my 75 for the PTQ that was coming up in a few days.

My brain immediately went to Dragon's Rage Channeler as the perfect card for this sort of list. It filters your deck to find Doomsday when you need it (and bin it when you don't), fills your graveyard for Murktide Regent, attacks alongside the dragon to deal 20 damage (especially when combined with Temporal Mastery). It also enables some really clean Doomsday wins (Temporal Mastery, bin a card, Temporal Mastery, bin a card, Thassa's Oracle).

Once I added a color to this deck, I couldn't support basic lands, and I converted the Dark Rituals into Lotus Petals to support the color requirements, as well as play nicely with DRC's surveil and delirium abilities. I went 5-0, 4-1, and 4-1 in leagues to vet and tune the deck, and played the following list in the PTQ:

I ended up 6-3, beating Reanimator, UR delver twice, Death & Taxes, Oops All Spells, 8-Cast, and lost to some explosive draws from Turbo Karnforge, fast protected kills by a Turbo Doomsday build, and lost games 2 and 3 to a Hogaak deck when i couldn't find Leyline of the Void despite mulliganing low. In summary, I won every game the deck played Magic, and that's remarkable.

That same day, Yamayama won the Saturday challenge with the following UB Tempo Doomsday list:

The Crusher

With my previously established bias against the cycling spells, and seeing 0 Temporal Masteries in the winning list, I concluded that Malevolent Hermit must be really fucking good. I made a few changes from Yamayama's list before launching it into a league:

• Cyclers out, Temporal Masteries in.
• Add Liliana the Last Hope to the main deck as another thing to Dark Ritual out, act as recurring removal, regrowing creatures (Baleful Strix is a prime target), and do some cute things with the -2 ability and Doomsday piles.
• Cut the 4th Dark Ritual for the first Lotus Petal. I like the Lotus Petal as a way to accelerate out the fair game plan, such as play a Baleful Strix around opposing Daze, or leave up a Malevolent Hermit activation.
• Cut Shelldock Isle / Emrakul, the Aeons Torn from the sideboard. There isn't a control deck in the format that doesn't play a bunch of Wasteland or Teferi, Time Raveler. I don't think the plan works consistently enough to be worth 2 sideboard slots.
• Add Stifle and Brazen Borrower to the sideboard (more on these cards later).

I proceeded to enter a league and rattled off the easiest 5-0 I've had since Underworld Breach was legal. And despite how good I thought Malevolent Hermit might be, it somehow outperformed even those expectations. It reads like Allosaurus Shepherd and plays like Uro, Titan of Nature's Wrath. Its front side is a relevant clock, and its activated ability of "U: Counter target noncreature spell unless its controller pays 3," as an ability, is functionally "uncounterable" back. It even works while the opponent controls a Teferi, Time Raveler. The back side is just as good, as a 2/2 Flying body that makes all of your noncreature spells uncounterable, incidentally beating things like Chalice of the Void. It's pretty trivial to win with Doomsday when your opponent can't counter any of your stuff. It's also worth noting that Cavern of Souls on Wizard works for both sides of Malevolent Hermit while still working for Thassa's Oracle.

This deck doesn't seem to lose. At the time of writing, I'm at 22 wins and 3 losses with the deck, with the ability to trace all 3 losses to mulligan or play decisions that I made.

How is this deck so good? It turns out that Delver decks (or more broadly, Blue tempo decks) and Doomsday have opposite matchup profiles, and you can change roles to play as whatever deck your opponent doesn't want to face. Against GW Depths or Death and Taxes, you're a Doomsday deck. Against Delver, you're a UB tempo deck that swings the pseudo-mirror with a pile of Baleful Strixes and (postboard) Leyline of the Void. Against Delver in Game 1, you can even Cavern of Souls on Dragon to make sure your Murktide Regents can take over the game. I don't think there's a deck that's actively good against both Delver and Doomsday, at least with Malevolent Hermit in the picture. No. Bad. Matchups.

It's nice that the two gameplans, while looking incongruent at first glance, actually have a ton of little synergies that let the deck play a lot more smoothly than it might appear to do on paper. Here's a few examples:

• Murktide Regent gets pumped whenever an instant or sorcery leaves your graveyard. Doomsday's resolution exiles all remaining cards from your graveyard and library, meaning that your Murktide Regents get pumped by however many instants and sorceries leave your graveyard at the time of resolution.
• Malevolent Hermit's body functions nicely for the fair game plan, and is innately a 2-for-1 as your opponent expends resources to (attempt to) answer both halves of the card. Meanwhile, either side effectively protects your ability to combo, and as mentioned before, Cavern on Wizard works here and with Thassa's Oracle.
• Temporal Mastery can turn a Murktide Regent into a lethal threat before your opponent gets a turn, and can be either set up by Brainstorm or by casting Doomsday and stacking your library. At this point, you stack a couple Temporal Mastery on top of your pile and still have the Thassa's Oracle as a contingency plan.
• Temporal Mastery also allows you to build functional Doomsday piles that beat Endurance (since Temporal Mastery exiles itself) and draw limiters like Hullbreacher (since you're taking extra turns and not drawing extra cards). To play around Endurance, for instance, a pile of Temporal Mastery, Temporal Mastery, Night's Whisper, Thassa's Oracle, Cavern of Souls casts Thassa's Oracle with an empty library and only 2 cards in your graveyard.
• The extra devotion granted by your creatures means that you can often play a Thassa's Oracle with extra cards in the library and still win through potential removal.

Card Choice Rundown

This deck is still pretty early in its development, but I'll give a rundown of the cards I think you can reasonably include and the reasoning behind them (sorted by mana cost, low to high)

Maindeck:

• 17-18 lands: Everyone's playing 17, but decks usually play 1-2 too few lands in the early stages of their development, and I can't see why this would be an exception.
• 4 Brainstorm and 4 Ponder: They're legal. Come on now.
• 3 Dark Ritual and 1 Lotus Petal: I brought up the split rationale earlier, and I like this split to hedge between the two game plans.
• 0-1 Unearth: Good for Doomsday piles if you're playing Predict or Consider, and great at recurring Baleful Strix and Malevolent Hermit.
• 0-1 Consider: Good with Unearth, and can be an extra cantrip to help smooth out a deck that's perhaps a bit on the clunkier side.
• 0-2 Preordain: Better than Consider at sculpting, worse than consider at feeding Murktide Regent or Unearth shenanigans.
• 0-4 Delver of Secrets: Pressures planeswalkers and combo decks. Cavern on Wizard. Removal magnet. I'm not sure if it's right to include actual factual Delver, but right now I'm playing 3.
• 0-2 Thoughtseize: Discards planeswalkers and combo pieces. Takes removal to protect your Murktides or countermagic for your Doomsday. As it's a liability against Delver, I'm currently not playing any, but could see that being wrong.
• 3-4 Daze: A great card in both the fair and unfair gameplans. The reason to play fewer than 4 is that the deck is pretty mana-hungry and casting a bunch of them early might not be feasible in order to get your 2-drops down in time.
• 0-1 Predict: Card advantage, good with Doomsday piles, good with Unearth, good with and against Delver of Secrets. The downside is that it's yet another 2-drop (see below).
• 4 Baleful Strix: A key part of not dying while digging through your deck. Also, Doomsday piles can sometimes be a few Baleful Strix followed by a Cavern of Souls and Thassa's Oracle.
• 3-4 Malevolent Hermit: While it's really good against Blue decks, it's legitimately bad against stuff like Death and Taxes. The reasons to play under 4 as a nonblue metagame concession or to thin out the number of 2-drops.
• 1-2 Night's Whisper: Card advantage. Can't be Pyroblasted. Important in that basic Doomsday pile of Temporal Mastery, Temporal Mastery, Night's Whisper, Thassa's Oracle, Cavern of Souls.
• 1-2 Thassa's Oracle: It has a trigger that says "win the game" on it.
• 4 Doomsday: Wins the matchups the rest of the deck doesn't.
• 0-1 Liliana, the Last Hope: Extra thing to use with Dark Ritual, repeatable removal, recurs your creatures, and can do cute things post-Doomsday like -2 with your last two cards in library (including Thassa's Oracle), which you then regrow and cast. In conjunction with Temporal Mastery, you can sometimes sneak up to 7 loyalty and ultimate before your opponent expects it, which, with few exceptions, does win the game. I'm not going to lie, this is a pet card of mine.
• 0-1 Sedgemoor Witch: It's a pet card, but not mine. I've seen some lists with it and it, like Liliana, is another non-Doomsday thing to combine with Dark Ritual. I'm not a fan of it because the ground creature decks can get much bigger than the Witch and the Insects can offer, while against Delver decks, as their entire threat-base flies, Sedgemoor Witch and the insects essentially read "can't block.
• 4 Force of Will: Controversial, I know.
• 0-1 Misdirection: For the fair gameplan, you can essentially play a 0-mana "2-for-2" where you misdirect your opponent's removal spell to their own creature. For the unfair gameplan, it functions as an extra Force of Will if you're protecting your own spells. The question becomes how many Force of Wills you want to play.
• 4 Murktide Regent: This deck is going to get Murktide Regent banned.
• 2-3 Temporal Mastery: The glue that holds this deck together. When drawn at non-ideal times, try to set it up for some massive combat combos with a mid-game Brainstorm or pitch it to Force of Will.

Sideboard:

In lieu of a sideboard guide (cards are too much in flux for me to actually map a 75), I will provide sideboard cards and the matchups they are for.

Alright, here's a little bit of sideboard guide: cut the entire Doomsday combo against Delver. It's closer to a liability, and you sometimes want to avoid even casting Doomsday in Game 1. That said, I do keep the Lotus Petal as a bit of a hedge against mana denial and as a tool to help cast stuff like Baleful Strix on curve without fear of Daze. Now back to the list of sideboard cards:

• 3-4 Leyline of the Void: Graveyard decks and UR Delver. It turns off both Dragon's Rage Channeler and Murktide Regent, neutering Delver's ability to generate a reasonable clock.
• 2 Fatal Push: Delver, creature decks, Hullbreachers.
• 2-3 Plague Engineer: Tribal decks, Delver (on Human), the mirror (on Wizard or Bird). Really good with Dark Ritual.
• 2 Force of Negation: Combo. Could also be Flusterstorm if you're less concerned about losing before you take your first turn.
• 2 Thoughtseize, 1 Duress: Combo and control.
• 1 Stifle: Great against opposing Thassa's Oracle triggers, but more importantly is instrumental at ensuring you can get to your own. Stifle stops Endurance, Thran Foundry, Ipnu Rivulet, Cephalid Coliseum, Fractured Sanity, and various other niche cards that people say on Twitter that Doomsday can't beat. It can also be used to disrupt key points in an opponent's gameplan like a Vampire Hexmage or Elvish Reclaimer activation, or a Craterhoof Behemoth or Kaldra Compleat trigger. It can still, of course, be used to grief opponents when it's in your opening hand, on the play, and your opponent is foolish enough to open on a fetch land.
• 1 Brazen Borrower: Mostly for Marit Lage and Hasty 5/5 indestructible Germ tokens, but is also good as a catch-all for various hate cards, while the 3/1 body plays nicely into the fair game plan.
• Other people are playing some copies of Opposition Agent, which is obviously great in the mirror, as well as against things like Urza's Saga and Green Sun's Zenith. I think they're good but am sadly still limited to 15 sideboard cards.

My Recommended List, Updated March 18, 2022:

Download link via MTGGoldfish

Piles:

This deck doesn't have any fancy piles. Night's Whisper draws 2 cards. Baleful Strix adds to the board and replaces itself. Temporal Mastery is a 0 mana cycler that lets you make extra land drops and exiles itself. Make sure you put Thassa's Oracle (and probably Cavern of Souls) in there, too.

Whether you're a fair Blue player, combo player, or a GW Depths player having an identity crisis, I hope this article gives you the resources you need to get started with UB Tempo Doomsday.