The matchup between Black-Green Delirium and White-Blue Flash is a hotly contested one. Before the tournament, some people told me that Black-Green Delirium was favored; others claimed that White-Blue Flash had an edge.
To learn more, I sought out the wisdom of seasoned pros who were playing one of these decks this weekend. I asked them who they felt was favored, what the key cards and interactions in the matchup were, and how they approached sideboarding.
We'll start with three Black-Green Delirium players, followed by three White-Blue Flash players. All of their answers are paraphrased.
Platinum pro (15) Joel Larsson: "I think it's favorable for Black-Green Delirium"
"It's hard to play against White-Blue Flash, but it's also hard for them to play against a good opponent who knows what their deck can do. In my experience, it's only their nut-draws that beat you, like when they curve into Gideon, Ally of Zendikar.
The match is a lot about Ishkanah, Grafwidow and Gideon, but I have Transgress the Mind and Tireless Tracker as ways to handle the planeswalker. Tireless Tracker can put you in a unique spot where you can attack Gideon on turn 4. Transgress the Mind is valuable not only because it can take Gideon but also because it gives information on whether they have countermagic. When you have Transgress, the match becomes way different—information is so good.
For my sideboard, I'm interested in bringing in 2 Natural State, To the Laughter, Transgress the Mind, Tireless Tracker, and Appetite for the Unnatural. As for what to take out, it's usually 2 Grim Flayer, 2 Mindwrack Demon, 1 Grapple with Past, and 1 Liliana, the Last Hope on the draw. On the play, Grim Flayer is worse versus Reflector Mage, and Mindwrack Demon cannot attack Gideon as well, so then choosing what to cut is way harder. I want to keep Grim Flayer in my deck, but I'm not entirely sure what to cut instead."
Platinum pro (12) Ondřej Stráský: "Black-Green Delirium is slightly favored, but it's close and the better player should win."
"I think that Black-Green Delirium just has better cards, and you have Emrakul, the Promised End which is the biggest end-game. You can also jam Grim Flayer on turn 2, and you'll win most of those games."
But the matchup is really tough, and I just lost a match to White-Blue Flash because I screwed up. There are so many things to play around—they have Stasis Snare, Spell Queller, and plenty of other cards. Ultimately, the most important cards are Iskhanah, Grafwidow and Gideon, Ally of Zendikar. Westvale Abbey is really good too; it's always hard to deal with, unless you have To the Slaughter or double Grasp of Darkness.
When sideboarding, I always take out 2 Grapple with the Past, 1 Liliana, the Last Hope, and 1 Mindwrack Demon. Then also a Ruinous Path or Pilgrim's Eye, as well as a Noxious Gearhulk on the play and a second Liliana on the draw. I board in 2 Natural State, 2 To the Slaughter, 1 Transgress the Mind, and 1 Tireless Tracker."
Platinum Pro (20) Petr Sochůrek: "It's 50-50, super skill intensive, and it comes down to who plays better."
"If the White-Blue Flash player is better, he's going to crush Black-Green Delirium, and it's the same the other round. I like the matchup because I often feel I can play it better than my opponent, but in my completely honest opinion, if players are equally good then it's 50-50 and can come down to individual card choices.
Every game is different because you have to re-evaluate everything on the spot. Sometimes they're really aggressive with Smuggler's Copter and sometimes it's a really grindy game. Sometimes I need to play Tireless Tracker early to play around Gideon, Ally of Zendikar, and sometimes I need to play a non-creature card to play around Reflector Mage. It all depends on the game state and my hand.
I usually board in 2 Natural State, 1 Transgress the Mind, 1 Tireless Tracker, and 2 To the Slaughter. What I board out depends on who is on the play: I always take out 2 Mindwrack Demon, 1 Pilgrim's Eye, and 1 Grapple with the Past, and then 1 Liliana, the Last Hope and 1 Noxious Gearhulk on the play and 2 Liliana, the Last Hope on the draw. The only thing I'm not sure about is if I should cut Noxious Gearhulk on the play. You don't want to get into a spot where they can sit behind counters—you have to go under them. But on the draw, you usually have enough stuff to play, so it's fine to have the more expensive card."
Gold pro Aleksa Telarov: "Green-Black Delirium has a small edge in Game 1, but White-Blue Flash has a bigger edge in Game 2 and 3."
"As a White-Blue Flash player, I feel slightly favored overall, but I think the matchup is pretty close. Especially if they spend their early turns on Vessel of Nascency, then they are too slow, and you should be advantaged. In Game 1, it's hard to deal with Ishkanah, Grafwidow. In Games 2 and 3, the countermagic in my sideboard gives me an edge.
The counterspells, in my opinion, are even more important than Gideon, at least after sideboard. If you just counter Ishkanah, then all of your other ways of attacking become live. Post-board games are always slower, and they have to respect your counterspells. For that reason, I like to keep land-heavy hands and don't mulligan as much. Even if I only have lands in hand, they may suspect I have a lot of counters and slowly play around them.
While sideboarding, I plan to add Spell Shrivel, Negate, Summary Dismissal, and Jace, Unraveler of Secrets. I cut Selfless Spirit, and depending on play/draw I may cut Spell Queller as well. I think you just want to have reliable hard counters, play Jace, and start to draw two cards per turn."
Steve Hatto, 9-1 at Pro Tour Kaladesh with White-Blue Flash: "Pre-board, it's pretty even. Post-board, the advantage should be with White-Blue Flash."
"I think the controlling sideboard of White-Blue Flash matches up very well against the grindy Black-Green Delirium strategy, but it's a lot about the specific configurations of the decks.
I think it's one of the more interesting matchups that Magic can produce, and both players can learn a lot about the game in general from playing or watching that matchup. It's all about the dynamics and a battle to get a better board position. Both players will try to resolve or protect a key spell like Ishkanah, and it's a dance to stick the relevant threat. You start fighting in the early game, and at some point the resources have been exchanged and someone wants to stick a planeswalker. It changes around all the time. Tireless Tracker may be irrelevant early, but eventually it will become a threat. So you have to plan for different angles from the beginning of the game, and it's a matchup where you can watch all those different layers with basic fair Magic cards.
My sideboard strategy is usually to board in the Angel package (Thalia's Lancers, Bruna, the Fading Light, Gisela, the Broken Blade) and I also like Jace, Unraveler of Secrets and counters in the matchup. Other than a very fast Grim Flayer start, they do not pressure you that much, and White-Blue Flash is good at keeping the early stage under control. I board out some Selfless Spirits due to Liliana, the Last Hope, but not all. And I used to de-sideboard Stasis Snare and Smuggler's Copter to blank their Natural State and to have a game plan that doesn't get hurt as much about Grasp of Darkness. "
Gold level pros Mattia Rizzi and Javier Dominguez: "The matchup is much closer than it looks, but it's slightly unfavorable for Blue-White Flash."
"It's funny you ask about this matchup, we were just talking about it!" they agreed when I found them in the feature match area. "Game 1 depends on Gideon, Ally of Zendikar. Our deck is built to have turn-four Gideon, but if you don't have Gideon, then you have a pile of cards. Meanwhile, if they are on the play, then a turn-two Grim Flayer is really good for them. Post sideboard, it goes slightly in our favor because of Jace, Unraveler of Secrets and counterspells."
"It's one of the best matchups to play in Standard; the games are always fun. Ishkanah is not always the problem because you can counter it with Revolutionary Rebuff. The problem is when they start recurring it in the late-game. Before we get to that stage, Reflector Mage is always good, especially against Tireless Tracker and Mindwreck Demon."
Sideboarding can depend on how they board and who is on the play. According to Rizzi, you never want Selfless Spirit in the matchup, and on the draw he doesn't want Smuggler's Copter. He cuts them for more interaction, like Declaration in Stone against Grim Flayer and Tireless Tracker, and to present fewer targets for Natural State. According to Dominguez, sometimes you can morph into a control deck, especially on the draw. If he goes control, then he cuts all copies of Spell Queller. Either way, there is a lot of freedom and wiggle room when it comes to crafting a post-sideboard game plan.
I did not find any consensus among the players I interviewed. Perhaps unsurprisingly, most of them claimed that the deck that they were playing this weekend held a small edge in the matchup that arguably defines Standard. Weighing all of their opinions as a whole, I think it's fair to say that it's a skill-intensive matchup, a close matchup, and that no deck is clearly favored. Maybe Green-Black Delirium is 51%, but skill and experience is a way more important factor.