Last weekend, I was able to sleeve up some new Modern Horizons cards, thanks to a semi-local tournament hosted inside of a convention. First prize was one of each of the Revised dual lands, which is too much value to turn down.
I waffled between which deck to play, but ultimately decided on updating Izzet Phoenix. With Bridgevine built and ready to go and a sick Mardu Pyromancer list on the drawing board, I settled on Phoenix because the new cards solved a lot of the problems I had with the archetype previously.
This deck carried me to a 5-0 start in the Swiss. After that, I double drew into Top 8, wandered around the convention, and won my quarterfinals match before agreeing to split for approximately $1000 worth of loot. It felt nice to be back!
Now that Pyromancer Ascension is out of the deck, you can shift your numbers around as much as you want. For example, if you wanted to get a maindeck Twisted Image in there over one of the other cantrips, you certainly could. A Snapcaster Mage or two could also be a fine addition.
Pyromancer Ascension was a powerful way to beat problematic permanents, such as Ensnaring Bridge, by ignoring them. That sort of effect is incredibly powerful to have access to, and it means you're attacking on multiple axes, which your opponents can't properly prepare for.
My all-star was easily Aria of Flame. I beat Rest in Peace; Narset, Parter of Veils; and a host of other problematic cards because of it. Despite your opponent gaining ten life, you should easily be able to kill them over the course of two or three turns by chaining cantrips together.
The most common reason people seemed apprehensive to try Aria of Flame is because your opponent gains ten life, which, in theory, could be problematic should they be able to remove Aria of Flame before it does any major damage. Since Aria of Flame is typically the last threat you cast, your opponent's counterspells and all-purpose removal spells will likely be taxed at that point.
With Pyromancer Ascension out of the deck, delve cards are fair game. There's still some graveyard interaction with Finale of Promise, Arclight Phoenix, and Faithless Looting, but you should be able to still delve and use those cards effectively.
Izzet Phoenix desperately needed a card like Magmatic Sinkhole, as it's used cards like Flame Slash, Lightning Axe, and Set Adrift to deal with large creatures before. Sinkhole has the added benefit of being able to ding planeswalkers for five, which should kill both Teferis; Jace, the Mind Sculptor; and Narset, Parter of Veils, even when they try to insulate them from Lightning Bolts and Arclight Phoenix attacks by keeping them at a high loyalty. It also deals with things like Lyra Dawnbringer that Azorius Control might try to sideboard in against you.
Beacon Bolt has some upsides, but it's largely outmoded at this point.
Lava Dart performed well, although I could see a world where we're still playing Gut Shot. You could make the case for either being stronger against Thalia, Guardian of Thraben (and Humans in general), but it basically comes down to whether you're on the play or draw. Given that you won't always be on the draw and the fact that you should have enough removal to keep your head above water, I'd rather have Lava Dart for the flashback, but there's merit to both.
While not an addition from Modern Horizons, Finale of Promise hasn't received much press due to the lack of Izzet Phoenix content after War of the Spark. Finale of Promise was a card people seemed excited for, but not one that ultimately made it into too many decklists.
Rather than your deckbuilding being constrained by Pyromancer Ascension, now it's dictated by Finale of Promise. Having the right mix of instants and sorceries is important, which is why I have Sleight of Hand instead of Opt. For the most part, you can find a good mix of cantrips, but not everything is as simple. If there's one thing I dislike about my decklist, it's that Finale of Promise doesn't have a sorcery-speed removal spell to utilize.
There's obvious tension between Lava Dart, the amount of Mountains, a low land count, and needing to use your mana each turn. Fiery Islet is another layer to that tension and I still haven't quite figured it out. My instinct says that eighteen total lands with one Fiery Islet should be good. You could make a case for a second copy with nineteen lands, especially with a slightly higher mana curve thanks to Aria of Flame and Finale of Promise.
Previous versions used to play Crackling Drake, but I was never about that life, so I tried to keep the curve as slim as possible. These new cards are so good that you gain a lot by playing them and it could be useful to increase the land count slightly.
That's one of the things I need to experiment with more, even if this configuration is "fine."
It should be no surprise that Force of Negation shows up here. It's been seeing play in basically every deck as insulation to some of the more unfair things people can do in Modern. From the Izzet Phoenix side of things, I mostly see it as a means to stop Azorius Control and Tron from resolving their big planeswalkers. Between Force of Negation and Magmatic Sinkhole, you can play a much longer game than you used to.
Force of Negation has a high cost, as Izzet Phoenix doesn't have raw card advantage, but it's often worth it for the tempo advantage against decks like Tron.
This won't cover all of the archetypes in Modern (because that would basically be impossible), but it should give you the framework to understand how to sideboard against nearly every deck out there. Each of the macro archetypes will be covered.
This is one of the few matchups where I'd prefer having a few more sideboard cards. It's not a matter of wanting to take out more cards, since I like most of the cards I have, but an Abrade, Flame Slash, or Anger of the Gods would go a long way toward making the matchup easier. If your opponent doesn't have graveyard hate, you don't really want the third Aria of Flame. You can remedy this on the play by bringing in a copy or two of Narset, Parter of Veils if you'd like.
A sideboard plan that consisted of Blood Moon and Shenanigans could be the cheat code for the matchup, but I don't like that plan very much. There are too many situations where either card is completely dead and I like the gameplan I have already.
I like having four pieces of graveyard interaction here for Arclight Phoenix and Pyromancer Ascension. Surgical Extraction is better against Arclight Phoenix but Ravenous Trap is better if they have Ascension and some delve cards. Your mix should depend on what your opponent has.
When you're sideboarding in three mana cards, you typically don't want the full amount of Faithless Lootings. I'd expect my graveyard to get attacked to some degree and don't want to draw too many cards that are resource negative.
The only thing that really matters here is having graveyard hate, although transforming a Thing in the Ice on Turn 3 could potentially do it against a weak draw.
VS Azorius Control
This is a matchup about patience and knowing when to try to turn the corner. The key moment will often involve baiting them into trying to resolve something, dealing with it immediately, and casting two threats.
While the Tron matchup was always close, it feels quite good now. Aria of Flame is a real win condition that doesn't use the graveyard and it happens to be something they are very weak against.
Despite facing graveyard hate here, you don't want to cut Faithless Looting because card advantage doesn't matter nearly as much as ensuring you have the appropriate tools.
VS Whir Prison
There are a few different ways to approach this matchup. The one I like the most is to ignore Goblin Engineer and fight Thopter Foundry / Sword of the Meek with Surgical Extraction. That way you don't need to keep mostly useless Lightning Bolts in your deck. Either way, you need to stop Urza, Lord High Artificer from coming online.
Izzet Phoenix surpassed my expectations. It had game against every single archetype and seems to be one of the decks that gained the most from Modern Horizons, at least from the already existing archetypes.
This list is close to perfect and one that I would highly recommend for any upcoming Modern event. I have some MCQs to play in this weekend at #MFSeattle, so it's possible that I'll get to run it back. Then again, I do want to try this new Mardu Pyromancer list I've been working on...