There’s an easy way to break tempo; the archetype just requires ways to turn a previously unused resource into something it craves and has little of. Tempo has no shortage of spare land drops or excess cards in the graveyard that we would gladly trade for more tools to win games with. Cards that offer these trades include Gush, which turns land drops into cards in hand; Treasure Cruise, which turns cards in the graveyard into cards in hand; Become Immense, which turns cards in the graveyard into damage; and Hooting Mandrills, which turns cards in the graveyard into an optimal threat. In Legacy, Threshold was tier 2 at best until Delver of Secrets saw print. The Insect perfectly exemplifies this principle; he rewards the deck for running a large volume of instants and sorceries, something it was going to do anyway.

Depending on the card pool of a format, some of these enablers can exist safely. Become Immense and Hooting Mandrills, for instance, don’t break Modern, in part because the format’s lack of a hyper-efficient, one-mana cantrip (Brainstorm, Ponder) and versatile, “free” permission (Daze, Force of Will) already makes tempo decks under-powered there. Treasure Cruise, on the other hand, broke the archetype not only in Modern, but in Legacy and Vintage, suggesting that cards are much more valuable a reward than either damage or big threats, defining cards as the only resource that truly makes tempo unbeatable.

Years before Khans of Tarkir, Tombstalker was a staple of legacy’s BUG Delver decks, but it never reached oppressive levels of representation. The spells that break the tempo deck always give it a way to refuel on cards without deviating from its gameplan. The only deck to have ever policed “broken tempo” decks with any kind of success is Vintage Stax, a deck designed to destroy Gush Aggro with insane plays like turn-1 Trinisphere. Historically, “broken tempo” has proven so difficult to interact with that Wizards has needed to ban or restrict key enablers (Gush, Treasure Cruise, Ponder, etc.). Modern is entering another era of “broken tempo,” this time fueled by Day's Undoing, which transforms an unused resource in tempo decks – the lack of cards in hand – into its dream prize: more cards.

After some games with UR Delver, I came to three conclusions that helped me establish iGrow’s core.

• Remand is already lackluster, and I can’t imagine how bad it will be in a faster metagame. It’s nice to have something to pitch to Shoal to counter CC 2 spells, but Shoal’s primary function is to counter one-drops. Vapor Snag handles the dangerous creatures (Goyf, Scooze) and Day's Undoing minimizes losses sustained from Terminate effects. Remand is only better than Mana Leak after multiple Undoings (in which case I’ve already won) or when I’m about to follow the counterspell with an Undoing (in which case I’m also about to win). Leak at least provides a hard answer to tricky permanents like Siege Rhino when I don’t have the sorcery handy.
• Two Faithless Lootings is too many. This card shines in grindy games; I had success with it in Counter-Cat last winter as “Treasure Cruise #5,” but drawing multiples in this deck hurts too much to justify a pair.
• 12 threats is too few. While Treasure Cruise Delver had no trouble treading water until it could Cruise into pressure, Undoing resets both hands symmetrically, punishing players who don’t impact the board before resolution. Hands without threats are basically as unkeepable as hands without lands, and I wouldn’t run only 12 lands. I tried Goblin Guide, but he was often too small for me. Missing the bulk of Monkey Grow’s beaters, I splashed green for a trio of Hooting Mandrills, and the deck immediately improved. However, without Thought Scour, they’d sometimes clog up my hand. Mandrills were also especially soft to Vapor Snag, which I expect a lot of in the coming meta.

I realized Tarmogoyf might not be bad in this deck. All of our threats die to Lightning Bolt anyway, so having one in the deck that only dies to Lightning Bolt some of the time seemed okay. I kept a single Mandrills (which consistently overperformed as a one-off) and settled on this list to begin my testing:

I won’t specifically discuss the “core” of the deck, because it’s basically the whole deck. The only two flex spots are Faithless Looting and Hooting Mandrills, which I tinkered with throughout my testing.

A quick note on the testing process before we dive into the game reports: I played 12 games against each deck, for a total of 36. Matthew Zielinski and I did three games each on the play and draw, both pre- and post-board. Twin, Burn, and Jund are all decks he’s comfortable with. Despite my experience with modern tempo decks, iGrow does play differently than Monkey Grow or Treasure Cruise Delver, and I’m sure I unknowingly made some crucial mistakes that ended up costing me games. (It may very well have more to do with the matchups, but my win percentages increased as we trudged through the gauntlet.) Regardless, I’m now convinced of this deck’s power. My record against Matt, in games, is 25-11.

UR Twin (60/40)

Day's Undoing not only restocks my resources against Twin’s attrition plan, it messes up any incremental advantage or library manipulation opponents gain with Snapcaster Mage, Electrolyze, Cryptic Command, or Serum Visions. Since Twin has such a high curve, I empty my hand much faster than my opponents, meaning Day's Undoing nets me many more cards. Twin’s high land count also gives its pilots “unkeepable openers” after certain Undoings, while I frequently end up with hands full of business.

Post-board, Twin becomes harder to beat, especially versions with red sweepers.
Tarmogoyf does some heavy lifting here, while the combination of Vapor Snag and Snapback (Gotcha!) makes it tough for Twin to combo off. That reduces the deck to its Keranos plan, which can’t keep up with Day's Undoing.

Twin does win when it draws ample removal, Spell Snare for Tarmogoyf, and permission for Day's Undoing. I lost one game to mana screw, and the others to attrition. In hindsight, it’s probably better to keep Day's Undoing mainboard regardless of whether I’m on the play.

Pre-board, on the play (3-0) 

Game 1 (win): Matt goes to 11 from an early Delver and I throw a Lightning Bolt at his End Step. Anther Bolt puts him to five, he fetches and then Electrolyzes the Delver. I Vapor Snag a Lavamancer but it resolves again and is joined by Pestermite in an attack on my own life total. I draw Lightning Bolt for exactly lethal.

Game 2 (win): Turn 2 Pyromancer into turn 3 Pyromancer. Matt Bolts my first in response to the second, but I exile a Probe to Shoal. I cast another Probe and a Bolt to end up with five Elementals. On turn four, I resolve Day’s Undoing with only a Tarmogoyf in hand to Matt’s 6 cards after he had cast Serum Visions. Matt untaps and casts Visions and a main phase Pestermite to get around Leak. I Snag it on my own main phase and play a 3/4 Tarmogoyf and Hooting Mandrills. Snagging Mite on my turn against a tapped out opponent is generally correct since it gets around Twin + Dispel. I don’t care so much about the “blowout” of my opponent losing a Splinter Twin; Day’s Undoing gets better when he has more cards in hand, and there’s no reason to risk a game already swung so deeply in my favor. Matt plays Lavamancer and is forced to Bolt a Token to survive the next turn, but I draw Swiftspear for exact damage.

Game 3 (win): (Matt mulligans.) I cast Swiftspear into Mandrills (after fetching, cantripping, and Probing) and both resolve. Matt tries to cast Pestermite to tap down Mandrills before attacks, but I Shoal it, exiling Day's Undoing. I attack and cast Tarmogoyf. Matt plays a Grim Lavamancer, which I Vapor Snag before attacking him down from 8 to 1. He tries to triple Bolt me with a Snapcaster Mage (I’m at 9 life) but I respond to the third Bolt by Snagging the Mage for that lethal point of damage.

Pre-board, on the draw (1-2) 

Game 1 (loss): (I mulligan.) I play Swiftspear after exiling Delver to Shoal a Lavamancer, but Matt has Bolts for Swiftspear and my turn-2 Pyromancer. I struggle to get another threat after exhausting those three. I eventually land a Tarmogoyf  but, it's too late; Matt combos off at 3 life.

Game 2 (win): (Matt mulligans.) Matt leads with a Visions, which I Shoal by exiling my own. He never drops another land and I take the game with Swiftspear into Pyromancer into double Bolt.

Game 3 (loss): (I mulligan.) We grind and interact. I get Matt to 4 life after resolving Day's Undoing. My 5/6 Tarmogoyf almost gets there, but Matt topdecks double Visions into Splinter Twin for his Exarch.

Post-board, on the play (1-2)

-1 Tarmogoyf
-1 Faithless Looting
+2 Snapback

Game 1 (win): (I mulligan.) I keep a hand of two Shoal, two land, Snapback, and Serum Visions. Visions finds me Pyromancer, which survives Bolt via Shoal, then Tarmogoyf and Delver. Matt Electrolyzes Pyromancer and Delver. I Snapback the Pyromancer in response, since I’ve drawn another Snapback to disrupt the combo. Matt then casts Exarch and I sneak in two damage with a pair of Elementals (bluffing a Bolt for his 1/4). At this point I have two cards in hand, but Matt only knows the Young Pyromancer. He taps out for Splinter Twin, and I Snapback his Exarch before untapping, attacking, and passing. Matt resolves Batterskull, but I Snag the token and attack for lethal.

Game 2 (loss): (I mulligan twice.) I’m stuck on a single Island with two Delvers and a Serum that never finds more land. I have no disruption and Matt gets the combo.

Game 3 (loss): Swiftspear and Pyromancer bring Matt down to 4 life. Anger of the Gods kills them. I have two lands in hand and slow-roll them to bluff any of my six bounce spells. Matt’s at four lands and goes for the combo anyway, which wins him the game. Turns out he had two more Twins in-hand and wasn’t under any pressure from my end, so I do agree with his play.

Post-board, on the draw (2-1)

-4 Day's Undoing
-1 Disrupting Shoal
-1 Faithless Looting
+2 Mutagenic Growth
+2 Snapback
+2 Mana Leak

Game 1 (win): Neither of us do anything for a couple turns. I Bolt a Pestermite, then Mana Leak an end step Exarch and then resolve Hooting Mandrills. After the Monkey draws first blood, I slam Tarmogoyf, and Matt raises me a Keranos. The God flips a Remand, which puts 3 damage on the 4/5 Lhurgoyf. I respond to an actual Lightning Bolt with Mutagenic Growth, growing him to 6/7. Matt taps out for Cryptic Command to counter the Growth and bounce Mandrills, and I tap out for Mana Leak. I attack him down from 9 to 1 and show Bolt and Snag for the concession.

Game 2 (loss): Matt curves out into Blood Moon and I don’t have any answers. (My current list includes a sideboard Forest, since fetching around Blood Moon proves simple enough should I expect the enchantment.) I still have two Swiftspears and a Pyromancer to apply pressure, not to mention Snapback for the combo, but Matt protects the combo with Dispel and goes off.

Game 3 (win): Delver flips off a Lightning Bolt and attacks into Matt’s own Lightning Bolt. Mutagenic Growth saves him and the Insect connects for five damage. I Leak an Exarch and cast Tarmogoyf. Another Exarch begets a Splinter Twin, but I Snag it and come in for exactly lethal with Snapback in hand.

Burn (65/35)

Pre-board games are tougher, since Gitaxian Probe can deal me some serious damage. Day's Undoing is mostly just dead (though I did exile it to Shoal for a Rift Bolt at some point); refilling Burn’s hand for them seems pretty bad to me. I expect Burn to run Undoing next season, meaning my mainboard Undoings will have added utility as Shoal food to counter my opponents’. I tested against Matt’s more-or-less stock Naya Burn list for this report, since an optimized Undoing build doesn’t exist yet.

Post-board, however, the matchup becomes laughable. The only game I lost was to mana screw on the draw. Feed the Clan, Forked Bolt, Tarmogoyf, and Young Pyromancer are all insane in this matchup. It helps that we don’t take much damage from our lands.

Pre-board, on the play (1-2)

Game 1 (win): Delver into Pyromancer into Swiftspear with double Lighting Bolt out-aggresses my opponent. Matt gets me to 5 life, but then floods out and I kill him.

Game 2 (loss): I keep a one-lander with Shoal, Bolt, and two Goyfs. I manage to kill two Swiftspears, but then draw three Probes in a row instead of lands and lose to a stream of Lava Spikes.

Game 3 (loss): Double Pyromancer into double Swiftspear makes me pretty confident. I Snag an Eidolon and a Grim Lavamancer and get Matt to 1 life, scrying a Bolt to the top of my library. His last two cards, a Boros Charm and a Lava Spike, take me from 7 to 0.

Pre-board, on the draw (2-1)

Game 1 (win): (I mulligan.) Matt draws a lot of lands and no removal for Pyromancer or Tarmogoyf. He Spikes me down to 4 but I hardcast a Shoal on Atarka's Command when his Goblin Guide attacks before swinging for the kill.

Game 2 (win): Matt has all “Bolts” (mostly Atarka's Commands), but can’t find enough lands to cast them all. I lead with Delver and Pyromancer and draw Tarmogoyf to round out the offense. An alpha strike and a Lightning Bolt win me the game.

Game 3 (loss): My opponent can’t find white mana and keeps passing the turn back. I eventually get a Goyf into play and take Matt to 4 life but a Lavamancer ends up pinging me one time too many.

Post-board, on the play (3-0)

-4 Day's Undoing
-4 Gitaxian Probe
-3 Vapor Snag
+1 Mana Leak
+2 Mutagenic Growth
+3 Feed the Clan
+3 Forked Bolt
+2 Threads of Disloyalty

Game 1 (win): I have a ton of threats this game: two Swiftspears, a Pyromancer, and a Tarmogoyf. I manage to kill two Lavamancers and my Elemental tokens double block a Goblin Guide. Feed the Clan during combat gives me lethal Prowess.

Game 2 (win): Delver eats Searing Blaze, but Young Pyromancer and Hooting Mandrills follow unscathed. Mandrills survives Volcanic Fallout then attacks for lethal over two turns.

Game 3 (win): I Forked Bolt a Lavamancer and cast Tarmogoyf. Matt plays Eidolon, which eventually blocks my beater. I cast Feed the Clan, then Hooting Mandrills, and Matt concedes with three cards in hand while I’m at 22 life.

Pre-board, on the draw (2-1)

(Same plan as for on the play)

Game 1 (win): Matt lands a Swiftspear, but then finds himself mana screwed. I have a pair of Swiftspears myself, and compliment them with a Pyromancer. Goyf and Feed the Clan sit in my hand since Goyf would only be a 3/4, but I don’t end up needing either card. Swiftspear blocks my Pyromancer; I Bolt the Swiftspear, Matt tries to save it with Atarka's Command, and I Mana Leak for the game.

Game 2 (win): I Forked Bolt a Goblin Guide and Matt rips three straight Eidolons. I Bolt the first one, Forked Bolt the second, and Threads the third while beating down with a Hooting Mandrills. Matt can’t cast much under my new Eidolon and Mandrills kills him.

Game 3 (loss): (I mulligan twice.) I keep Island, Delver x2, and Bolt x2. I draw Forked Bolt and Tarmogoyf while Matt has the dream: Swiftspear into Eidolon into Atarka's Command. Delver never flips and I never find a second land.

Build Tweaks - Part 1

I ran Faithless Looting to cycle lands after an Undoing, but I’d already be so ahead in those cases that it wouldn’t matter. Additionally, I often found myself making 4-6 land drops before casting the sorcery, drastically reducing the chances of drawing into too many lands with my new seven. When I drew Looting off an Undoing, I generally didn’t want to cycle any of the stuff I had in-hand. I cut it for a mainboard Mana Leak, since the card was sweet when I brought it in and I liked the idea of having a mainboard “no” for two mana.

I tried replacing Sulfur Falls with a Forest so I didn’t auto lose to Blood Moon, but the card was ultra bad in the mainboard, forcing a bunch of mulligans and creating some awkward draws. I moved it to the SB, adding a Blood Moon since I may as well run one if I can support it. Since the Burn matchup proved so favorable, I also cut a Feed the Clan for a Negate, which answers spells like Karn, Languish, and Ad Nauseam that can otherwise be tricky to Shoal.

-1 Faithless Looting
+1 Mana Leak

SB:

-1 Feed the Clan
-2 Mana Leak
+1 Forest
+1 Blood Moon
+1 Negate

Here's the updated list:

Jund (75/25)

Just as Treasure Cruise made a joke of modern’s infamous BGx decks, Day's Undoing morphs Jund from Delver’s worst matchup into one of its best. I want to say this deck won’t even exist a month from now because the card is such a beating. I do expect Abzan to rise meteorically in popularity as BGx pilots realize they need Siege Rhino, Lingering Souls, and Stony Silence to deal with Undoing-powered linear strategies. For this reason, the matchup proved bittersweet; when Shoaling Lilianas made me over-euphoric, nightmarish flashes of the Rhino promptly sobered me up.

Pre-board, on the play (2-1)

Game 1 (win): I play a Delver, and Matt Thoughtseizes my Tarmogoyf. I flip Delver with a Day's Undoing and play Swiftspear, two Probes, and a Bolt for 10 total damage. Matt plays a Goyf. I attack with my team and he blocks the Swiftspear, then I cast Undoing and state-based actions kill Tarmogoyf. Matt’s at 5 life now; he plays Scavenging Ooze and kills my Delver. I win on turn four with a new hand of Swiftspear, Snag, Bolt, Serum Visions, Undoing, and lands.

Game 2 (win): (Matt mulligans.) My two Goyfs and a Pyromancer bring Matt to 10 life before he resolves Olivia Voldaren and kills the Shaman. I attack with my Goyfs to put Matt at 6, and cast Day's Undoing to dig for two Lighting Bolts, both of which I find.

Game 3 (lose): Matt’s surprise Sword of Light and Shadow ends up killing me as I fail to find a second Undoing after my first one gets IoK’ed. 

Pre-board, on the draw (2-1)

Game 1 (lose): I keep a one-lander with two Goyfs and two Visions. I don’t make my second drop until turn five, by which time Matt has a Tasigur to kill me with.

Game 2 (win): Swiftspear and Tarmogoyf beat Matt up, and I exile an Undoing to Shoal his turn-three Liliana. He Terminates the Goyf next turn, but I have more, plus enough reach to kill him in two turns.

Game 3 (win): I land Delver and Mandrills before casting Day's Undoing to take away Matt’s Olivia. He Terminates the Ape in response, then taps out for a freshly drawn Huntmaster. I Vapor Snag it on the end step, cast a Lightning Bolt, attack, and Day's Undoing again. This one draws me two Bolts, a Swiftspear, and a Goyf, which prove more than enough to kill my opponent with.

Post-board, on the play (3-0)

-4 Delver of Secrets
+2 Threads of Disloyalty
+2 Snapback

Game 1 (win): I have two Swiftspears and Probe to pump them. Matt Bolts one in response to the prowess trigger, but I Shoal and attack for six. He finds himself at 10 life somehow and I rip my second land for a Tarmogoyf. Not wanting to risk an in-combat Kolaghan's Command taking the one card in my hand, I cast a pre-combat Day's Undoing, since Matt’s down to only 2 life. I Shoal his Inquisition, but a second one takes my Bolt; I still cast Goyf and Mandrills, which obviously get there.

Game 2 (win): I open with three Tarmogoyfs and draw the fourth with a first-turn Serum Visions. I start casting them and attacking. Matt tries to stop the onslaught with Goyf+Bolt, Abrupt Decay, and Liliana, but of course nobody beats that many Tarmogoyfs. Close to death, he resolves a Huntmaster, and I Threads the Wolf token to attack for lethal after chump blocks.

Game 3 (win): A slow start from both of us. I Mana Leak a Thoughtseize to play out a Bolt-proof Tarmogoyf and Matt plays a Scooze. I Threads it, but Golgari Charm eats my enchantment. I Vapor Snag the Scooze before it does too much damage to my Lhurgoyf, but after it eats all of the creatures. I drop Swiftspear, Bolt Matt’s face, and attack. I draw into two more Goyfs and Matt resorts to chumping before I kill him.

Post-board, on the draw (2-1)

(Same plan as on the play)

Game 1 (win): Matt’s Liliana has me sacrifice a Pyromancer, but I have another and a Tarmogoyf to continue the beats. My opponent has Goyf in play and resolves a Fulminator Mage after I attack him directly. I attack again with my Goyf, and Matt blocks with Fulminator, sacrificing it before damage to destroy my Steam Vents. I respond by tapping the Vents to Snag Matt’s Goyf, and play a post-combat Day's Undoing. Matt plays Jund Charm and sacrifices Liliana to wipe my board, but he’s at just 6 life. I play a Pyromancer and cast Undoing again, which draws me Lightning Bolts.

Game 2 (loss): With two Goyfs in hand, I attack into Matt’s Goyf with my Swiftspear and Bolt the Lhurgoyf before damage and after blocks. Matt blows me out with Abrupt Decay, putting me on the back foot before I can stabilize. I foolishly block his Goyf two turns later with my own, even though I’m at 15 life; Matt has Kolaghan's Command to destroy my creature after damage and follows his play with a Huntmaster of the Fells. We fight over it – Threads, Decay, Threads – but Matt controls the flips better than I and the Werewolf kills me. I never see an Undoing.

Game 3 (win): (Matt mulligans.) My opponent plays a tapped Ravine, and I play a tapped Vents. He plays another Ravine; I cast Pyromancer and pass the turn, saving my Probe for Disrupting Shoal. Sure enough, Matt tries to Bolt on my end step and is met with the counterspell. He tries a main phase Kolaghan's Command, but I Shoal again, this time exiling Day's Undoing. I untap, attack for 4, and play a Tarmogoyf. Matt casts a Tasigur, but I Snag it. He eventually resolves Jund Charm to wipe the board, but my huge Goyf survives and destroys him.

Build tweaks - Part 2

While I liked Hooting Mandrills and Mana Leak in my mainboard, I felt there could be better options. I remembered losing games if I didn't draw Day's Undoing and wishing I had more consistency tools. I also lamented the games I lost to mana screw. I figured I’d have to cut Leak (weaker than Mandrills) for a 19th land, but that would push my instant/sorcery count down to just 24, a number that didn’t appeal to me. Then, while re-reading a Menendian article on Vintage Grow, my attention was drawn to an old favorite of mine: Sleight of Hand. I’ve done some undocumented testing against less popular decks since Tuesday (Elves, Infect, UW Control, etc.), and Sleight pulls its weight. Early on, it finds my second land, while later in the game, it’s the greatest topdeck.

The sideboard also underwent some changes. Mutagenic Growth isn’t a card I want even against Lightning Bolt decks like Jund, so I cut them entirely. Destructive Revelry seems better than Grudge if my graveyard gets shuffled back into my deck often enough, and its damage bonus adds up fast if I’m playing them over and over. Besides hosing Affinity and Bogles, it provides a flexible answer to random midrange cards like (Vedalken Shackles and Choke). I also elected to try a Staticaster, who hasn’t disappointed me yet. In an Undoing game, having a free, repeatable source of damage to wipe Elemental tokens, Lingering Souls Spirits, Llanowar Elves and other dorks, or even Signal Pest greatly appeals to me.

-1 Hooting Mandrills
-1 Mana Leak
+2 Sleight of Hand

Sideboard:

-1 Ancient Grudge
-2 Mutagenic Growth
+1 Izzet Staticaster
+2 Destructive Revelry

Here's the newest version:

After reading my recent Nexus articles, many players at the local game store are annoyingly hoarding their copies of Day's Undoing. Assuming I can find a fourth copy for the upcoming double-PPTQ weekend, I’ll be back next Friday with some tournament reports.