Dredge is the new Affinity.
Dredge has steadily increased in popularity since the unbanning of Golgari Grave-Troll. The deck continues to become more and more refined as new cards like Prized Amalgam and Haunted Dead give it more tools to work with. This weekend the deck finally had its breakout performance with Ross Merriam winning the Syracuse Open with a Greater Gargadon + Bridge from Below build, a list nearly identical to the one Justin O'Keefe quietly won an SCG Classic with a couple weeks prior. I have faced no deck more than I have Dredge in Magic Online Leagues over the past couple weeks and I can now say with confidence that there is a new "best linear" deck in Modern, a deck with an even higher game 1 win rate than Affinity and a deck that will almost assuredly run you over if you don't dedicate specific hate for it in your sideboard. Yes, Dredge is the new Affinity!
The basis of the deck is to put dredge cards in the graveyard and dredge them back to fill the graveyard with all the other cards in the deck that provide a bonus from the graveyard.
When you dredge Narcomoeba into the graveyard it returns to the battlefield immediately. This triggers all copies of Prized Amalgam to return on the next end step. If you play a land, all your Bloodghasts will return immediately, which also trigger Prized Amalgam. If Haunted Dead is in the graveyard, you can discard two cards to bring it back, which is another way to trigger the Prized Amalgam.
Shriekhorn will mill 6 cards over the course of three turns for just 1 mana. It also has Insolate Neonate and Faithless Looting to put cards into the graveyard while also "drawing" extra cards, which usually means dredging more cards instead. Flashing back Conflagrate is yet another way to discard cards while also dealing with problematic creatures such as Scavenging Ooze or Kalitas, Traitor of Ghet.
The final piece to the puzzle is Greater Gargadon and Bridge from Below. This combination allows the deck to make tons of Zombie Tokens in a single turn, even off just one Bridge from Below, since the deck has so many expendable creatures to sacrifice that come right back. It's also built-in protection from cards like Anger of the Gods.
The sideboard mostly consists of three things: ways to win the mirror, ways to beat burn, and ways to beat graveyard hate. The only way anyone realistically beats Dredge is through graveyard hate, burn, or Dredge.
Given that Dredge was already on the rise and is now coming off its breakout weekend, I expect an explosion of Dredge decks in the coming weeks. I consider it THE deck to beat right now in Modern. This means two things for the metagame: you must dedicate enough cards in your 75 to beat Dredge, and decks that match up well against Dredge will rise in popularity while those that do not will decline in popularity. There are also some incidental effects that will likely occur. For instance, with Dredge now occupying the space in the metagame Affinity used to enjoy, artifacts will have less of a target on their backs than graveyards. So artifact-based decks like Lantern Control and Affinity have a much better chance to flourish than graveyard-based decks like Living End and Goryo's Vengeance.
Let's go through the metagame and consider which decks are good to play right now and which are not, in light of the impact dredge is making on Modern.
Jeskai Control with Nahiri, the Harbinger to find Emrakul, the Aeons Torn is the best Snapcaster Mage deck in Modern. The Nahiri, the Harbinger element offers a "combo" dimension that other control decks lack and therefore affords the deck more inevitability than other control decks have. Grixis is second-best, and could adapt to Dredge by playing Leyline of the Void in the sideboard, but I think Jeskai with Rest in Peace in the sideboard is overall the best Snapcaster Mage control deck right now. Sphinx's Revelation and Sun Titan are powerful cards, but are not where you want to be right now. If you want to play Control, play Jeskai Nahiri.
Merfolk has been a contender in Modern for years, but it has been especially popular in recent months and I expect this trend to continue. It's a deck that can go wide while also going big since the merfolk lords all pump each other. They also have built-in evasion via islandwalk in conjunction with Spreading Seas and Sea's Claim. These Island-makers also disrupt opposing mana development, especially in a format defined by fetchland/shockland manabases. In addition to disrupting opposing mana, the deck plays just enough disruption to give an opponent a headache and also uses Kira, Great-Spinner to make one-for-one targeted removal a much less effective plan to combat the pile of lords strategy.
I expect Grafdigger's Cage to go for 2x to 4x as it is the most effective graveyard denial card available to mono blue against Dredge.
In addition to Merfolk, Affinity is the other linear aggro deck that goes both big and wide. Both are excellent choices right now, though for different reasons. Affinity can afford to board in a pile of Grafdigger's Cages because the extra copies can just be sacrificed to Arcbound Ravager or at least can sit around and fuel Master of Etherium and Cranial Plating.
Ghirapur Aether Grid is a great answer to Stony Silence while Galvanic Blast gives the deck a way around Kataki, War's Wage. Spell Pierce answers Creeping Corrosion and Shatterstorm while Dismember and Spellskite give the deck an edge against Infect. Like Dredge, Affinity is good at combating hate. Also like Dredge, if you don't pack hate, you will get rolled over. So it makes sense that most of the sideboard is dedicated to beating hate rather than hating other strategies. And with graveyard hate becoming more necessary, I suspect some of that space will be freed up by lessening the graveyard hate. This could only mean good things for the robot tribe!
Bant Eldrazi is the best midrange juggernaut right now, eclipsing both Jund and Abzan On pure power level, Bant Eldrazi about the same as Jund and Abzan, but it relies much less on its graveyard than either of those decks since it uses Thought-Knot Seer, Reality Smasher, and Drowner of Hope instead of Tarmogoyf and co. to finish the job. The only card in the deck that can be adversely affected by graveyard hate is Matter Reshaper. I also love running the full four copies of Grafdigger's Cage in the sideboard. I expect this to become a normal trend in Modern for the foreseeable future. I would like to see a little more sideboard hate for Affinity than just 2 Stony Silence though.
One of the only decks in Modern that can legitimately race Dredge and Affinity is Infect. I would run it over Bogles, Storm, Elves, Ad Nauseam, or any other non-Dredge linear combo deck right now. Winning consistently by turn three is important, as is being able to win through a ground overtaken by zombie horde. Infect can do this with Blighted Agent, Inkmoth Nexus, or Distortion Strike. Despite all my rage, I would still run more than 1 Grafdigger's Cage in the board.
As with Infect, Burn is one of the few decks in Modern that can consistently race Dredge. It's also similar to Dredge in that its sideboard is primarily devoted to beating hate cards rather than hating out other strategies. Destructive Revelry is a necessity against Leyline of Sanctity, Skullcrack against life-gain spells, Path to Exile against creatures that gain life such as Kalitas, Traitor of Ghet or Spellskite. Kor Firewalker is for winning the mirror, and Grafdigger's Cage is actually for preventing Dredge from flashing back Gnaw to the Bone, in addition to being useful against Kitchen Finks recursion in Toolbox decks. I would definitely play Naya Burn over Death Shadow or other Zoo-type decks. The turbo burn plan is the best right now since attacking on the ground through zombies should not be a necessary part of your strategy. If it is, you might have a bad time.
Among the Toolbox decks, I think Naya Kiki-Chord is the best one right now. Unlike Abzan Melira, it doesn't rely on the graveyard for its combo. It does, however, get hurt by all the Grafdigger's Cages that are skyrocketing in popularity as a way to fight Dredge. Collected Company, Chord of Calling, and Eldritch Evolution are therefore much less appealing right now than they otherwise would be.
The Bant Knightfall decks are similarly impacted, but less so. Knight of the Reliquary is probably still not the best creature to play with right now amidst a field of Leyline of the Voids and Rest in Peace. The deck also is not consistently fast enough to race Dredge or the other handful of decks that can. I would therefore not recommend it unless you have a specific plan to fight the decks in this article or are a master like Eli Kassis.
The big mana ramp decks are also not especially well-positioned right now. Anger of the Gods and Ugin, the Spirit Dragon are ineffective against the Greater Gargadon + Bridge from Below plan. Perhaps a Tron deck packing Grafdigger's Cage and Relic of Progenitus could work, but I'm not holding my breath.
Also the finesse creature decks such as Martyr, Faeries, and Delver just feel like worse versions of other decks in the format right now. For instance, Delver is worse at the burn plan than Naya Burn, worse at being a Snapcaster Control deck than Jeskai Nahiri, and is slower than the linear combo decks that can actually hope to race Dredge.
Lastly, I would not run Living End or Goryo's Reanimator right now, mostly because graveyard hate has increased considerably in popularity. Living End dodges Grafdigger's Cage, but it loses to Rest in Peace and Leyline of the Void. If nothing else, Dredge decks run four Leyline of the Void in their sideboard for the mirror and you will therefore have a very difficult time against Public Enemy #1. If you're going to play a deck that's soft to Leyline of the Void, it's very likely better to just play Dredge.
So in no particular order here are the 7 decks I would recommend right now:
As is always the case, if you have a pet deck and you have a plan to fight these 7 decks, by all means stick to your guns and persevere (as I have been doing with Hatebears). But if playing one of these seven decks is a possibility and your goal is to win the tournament, I'd recommend choosing from this short list of top contenders.