Synopsis
Infect is a beatdown strategy that primarily takes advantage of efficient creatures with the Infect mechanic, like Glistener Elf, Blighted Agent, and Inkmoth Nexus, alongside pump spells like Might of Old Krosa and spells that protect said creatures from opposing removal like Blossoming Defense. Infect’s ideal game plan is to land an early creature and end the game as quickly as possible by casting a lethal combination of pump spells on that creature. Although creature removal is extremely common in Modern which can make piloting Infect very tricky, the deck’s core has the tools to give its pilot more than a fighting chance in the face of common disruption like Lightning Bolt, Path to Exile, and Fatal Push.
While Infect’s general game plan has similarities to traditional aggro strategies in that it plans to deploy cheap creatures and win in the combat step, it tends toward a play pattern where pilots will want to set up a turn where they “combo off” with multiple pump spells and end the game on the spot. In this way, Infect plays sort of like a spell-based combo deck, with the combo being an attacking, unblocked creature and enough pump spells to reach 10 or more poison counters.
Core Cards
Glistener Elf and Blighted Agent are arguably the most efficient Infect creatures, costing 1 and 2 mana respectively. There are other 2-cost Infect creatures, but Blighted Agent’s evasion means it gets the nod over other options. Inkmoth Nexus rounds out the Infect creature suite, which is essentially a zero-mana threat that dodges sorcery speed removal and is difficult to block. Infect decks also play Noble Hierarch as a way to get ahead on mana early so multiple spells can be cast in succession, and because Infect creatures effectively benefit doubly from Exalted triggers.
Support Cards
Pump spells commonly included in Infect are Might of Old Krosa, Mutagenic Growth, Groundswell, Distortion Strike, and Become Immense. Blossoming Defense and Vines of Vastwood pull the double duty of being both pump spells and protection spells, and are among the strongest spells in the deck. Other less specific disruptive/protective spells are often included in Infect decks, such as Spell Pierce, Apostle’s Blessing, Twisted Image, and Dismember.
Mana Base
Infect’s mana base is usually composed of 9 fetch lands (must be able to fetch Forests, so some combination of Wooded Foothills, Windswept Heath, Misty Rainforest, and Verdant Catacombs), 2 Breeding Pools, 2 basic Forests, 4 Inkmoth Nexus, 2 Pendelhaven, and 1 Dryad Arbor. The seemingly high fetch land count is so you often have fetch lands in your opening hand and are able to fill your graveyard quickly to cast Become Immense as soon as possible, as well as having access to many lands that can potentially fetch a Dryad Arbor if need be. Dryad Arbor is a multi-purpose tool that can be grabbed with your fetch lands. It can chump block in a pinch, protect you from sacrifice effects like Liliana of the Veil’s -2 ability, and can even be fetched on your opponent’s end step to serve as a surprise attacker alongside some pump spells against an unsuspecting opponent who is careless with their life total. Pendelhaven is a good fit for Infect, being a source of green mana, and also pairing conveniently with all of your Infect creatures as a way to give them additional power and toughness given they are all base 1/1.
Strengths
Infect excels in metagames where efficient creature removal is not a common feature due to decks like Tron being dominant. When decks like Tron or Scapeshift are common, which prey on removal-oriented midrange and control decks but tend to fold to spell-based combo, fast beatdown decks like Infect can take advantage of the lack of creature removal with some of the fastest creature-based kills out there. It is difficult for decks not fully committed to killing small creatures to effectively combat Infect’s combination of a fast clock and protection/disruption, so in metagames where decks are attempting to go too big or sail past each others’ plans to the finish line, Infect is a very good choice.
Weaknesses
Infect tends to have a difficult time beating tempo, control, and disruptive midrange strategies. These strategies are usually effective at stopping a fast kill from the Infect deck, then closing the door by establishing a clock of their own or gaining insurmountable card advantage. These matchups are not impossible and can be improved tremendously after sideboarding, but a metagame populated solely by decks of this sort is not one where Infect will thrive, generally speaking. Infect also specifically has a very hard time beating Burn because their burn spells double as removal for your creatures, and Eidolon of the Great Revel is nearly impossible to deal with in an effective manner.
Sideboarding
Infect sideboards usually include matchup-specific disruption or hate cards, additional protection spells, and sources of card advantage for matchups where games are likely to go longer. These are the more common sideboard options.
Dispel is a strong inclusion against control decks with lots of counterspells and removal. Also very good against Burn and specific spell-based combo decks.
Shapers’ Sanctuary is a card advantage engine that allows you to power through your creatures being removed repeatedly. Often times control and midrange opponents will trim down on late-game payoffs and card advantage of their own against Infect because they fear dying before those cards become relevant, and consequently they have a hard time keeping up with a card like this in a long game.
Relic of Progenitus and Grafdigger’s Cage are effective options for combating graveyard strategies
Viridian Corrupter is artifact removal that comes attached to an Infect creature and can be Maindeckable in some metagames.
Spellskite is excellent for protecting your infect creatures from removal, especially Lightning Bolt and Lightning Helix, which don’t outright kill Spellskite. Pairs especially well with Shapers’ Sanctuary.
Dissenter’s Deliverance is flexible artifact removal that can be cycled away when not effective
Nature’s Claim gives the deck unconditional artifact and enchantment removal with a drawback that the Infect deck doesn’t care about
Wild Defiance is effective at combating damage-based removal like Lightning Bolt. Also makes it very easy to cobble together a lethal attack, even if you have access to few resources.
Echoing Truth is a catch-all for problematic permanents or something like Empty the Warrens tokens
Nissa, Voice of Zendikar is a Planeswalker that can be played as early as turn 2 with the help of Noble Hierarch. Plant tokens make effective blockers against decks like Death’s Shadow, which are difficult matchups, putting +1/+1 counters on multiple creatures can be very powerful, and if left unanswered amidst you throwing an onslaught of Infect creatures in your opponent’s face, she gets to ultimate pretty quickly which is probably game over.
Kitchen Finks acts as a resilient threat that is specifically good against Burn decks which are extremely difficult to beat with Infect’s regular game plan.
Dismember is the best removal available and most Infect decks play 1 of these maindeck, but you are likely to encounter matchups where you want multiple copies.
When sideboarding with Infect it is important to identify what angle your opponent is coming from to try to beat you. If they are trying to beat you with a critical mass of removal, pump spells that don’t protect your creatures are probably bad to have too many copies of and should be replaced with something else out of your sideboard. If your opponent is only trying to race you, your pump spells and matchup-specific disruption are very important. Most of the time your opponent’s plan will be somewhere in the middle of this dichotomy and you will have to find the right balance of different elements for the situation. In this writer’s opinion, the only thing that isn’t fair game to sideboard out is your creature core Glistener Elf, Inkmoth Nexus and Blighted Agent as without these creatures, your deck does basically nothing.
General Tips:
The timing of your pump spells is going to be crucial to your success with Infect, and is going to change depending on what your opponent is representing and/or is likely to have. Against control or midrange opponents who are likely to have removal, you are generally going to want to wait until you have multiple protection spells for backup or they are tapped out to go for a combo-kill.
Against opponents you know are unlikely to have meaningful interaction however it is usually correct to fire pump spells off freely to kill them as quickly as possible. A good train of thought to get into the habit of rehearsing with Infect is “If they have nothing meaningful, can I kill them this turn? How likely are they to have something meaningful? If they are likely to have something, what should I do? Can I allow some of my creatures to die and save protection for a more critical turn later? Can I trick them into an exchange that is beneficial for me?” etc.
Beating Ensnaring Bridge is extremely difficult for most beatdown decks, but Infect conveniently has access to Noble Hierarch, which can attack even if opponent has Ensnaring Bridge and 0 cards in hand, and still deal damage to them due to Exalted triggers. Noble Hierarch is a massive problem for decks playing Ensnaring Bridge because they generally don’t plan to win quickly, so it can usually get the job done with the help of some pump spells.
The Future of Infect
For future prints, the deck could gain better pump spells like it did with the printing of Blossoming Defense. New Infecters aren't being printed and Noble Hierarch is not going to be outclassed anytime soon; that only leaves the pump spells and protection spells as a place for possible upgrades.
Infect has been a roleplayer in the Modern format off and on but is powerful enough to generally be an okay choice at worst. When Big Mana decks cycle back to the top, Infect is a great choice to knock them off of the top of the pile. This makes Infect a valuable deck to be familiar and comfortable with and a good one to have on the shelf ready to go.