Infect in MTG: Rules, History, and Best Cards

Last updated on March 21, 2024

Triumph of the Hordes | Illustration by Izzy

Way back in the Time Spiral block we were shown a pair of timeshifted cards with a strange new ability: poisonous. This was not only a callback to the poison counters that were sporadically printed between Legends and Visions, but also a precursor to the future: infect.

Infect was a major Scars of Mirrodin mechanic and forever changed the landscape of the game because of it. But what else is there to know about this mechanic? Let’s take a look!

How Does Infect Work?

Phyrexian Unlife | Illustration by Jason Chan

Whenever a creature with infect deals damage to a creature, it puts a number of -1/-1 counters equal to that damage instead of dealing actual damage. If a player is dealt damage by a creature with infect, that player gains that many poison counters. If a player has ten or more poison counters, they lose the game.

History of Infect

While poison counters aren’t entirely unique to infect, the mechanic wouldn't be introduced until Scars of Mirrodin was released in 2010. Mark Rosewater has a famous obsession with the poison mechanic.

Tempest was originally supposed to be a poison-themed set before it was cut from design.

Scars of Mirrodin featured infect as a primary mechanic, with Skithiryx, the Blight Dragon as one of the best. Infect returned in both Mirrodin Besieged and New Phyrexia but hasn’t been printed since. Thanks to Phyrexia: All Will Be One, poison lives on in toxic.

What Colors Is Infect in Primarily?

Infect is primarily a keyword for black and green cards like Tainted Strike and Putrefax. It also appears on some artifacts and was featured on a small handful of red, blue and white cards in New Phyrexia.

Is Infect Evergreen?

Infect is not an evergreen keyword, and most signs point to it never becoming one. Because of how difficult the mechanic is to balance and how it's tied to the Phyrexians, it's unlikely we’ll ever see the keyword outside of sets themed around Phyrexia.

Are Infect and Poison Counters the Same?

Yes and no. Infect grants poison counters to players, just like some older cards do. Poison counters gained from Grafted Exoskeleton and Branchblight Stalker are identical to Virulent Sliver.

Infect vs. Poisonous

“Poisonous” was the keyworded ability for two timeshifted cards, Snake Cult Initiation and Virulent Sliver. Unlike infect, this keyword only grants poison counters when combat damage is dealt to a player and that damage isn’t prevented. It also has a value associated with it, meaning that multiple instances of poisonous can grant multiple counters.

Infect vs. Wither

Wither was half absorbed into infect’s design. Creatures with this ability don't grant poison counters but they “wither” them away when they deal damage to another creature, adding -1/-1 counters instead of dealing damage. Infect does the same thing to creatures with the addition of poison counters to players while creatures with wither deal regular combat damage to players.

How Many Poison Counters Is Lethal?

Per the Comprehensive Rules 104.3d, if a player ever has ten or more poison counters, they lose the game. This rule has been changed for Two-Headed Giant games where a team loses the game if they have 15 or more poison counters.

Do You Still Lose Life to Infect?

Unlike poisonous and toxic, there’s no loss of life when a creature with infect deals damage to a player. Per 702.90b, the infect damage dealt does not result in a loss of life, instead that player is given that many poison counters.

Does Infect Still Count as Damage?

Yes, and no. It's a little bit of a confusing mechanic. Whether a creature, planeswalker, or player is dealt damage by a creature, the result is different. Damage is still dealt, but it may end up as -1/-1 counters or poison counters, or just plain damage (to planeswalkers).

It still triggers on-hit effects like lifelink, or triggered abilities that rely on a creature dealing damage.

Does Preventing Combat Damage Stop Infect?

Yep! It sure does. As explained before, infect is still combat damage. If you can prevent it with a fog, you should.

What Happens When You Damage a Planeswalker With an Infect Creature?

This is about the only scenario where infect doesn't do anything different. Unlike when dealing damage to creatures or players, planeswalkers just take damage like they would in any other scenario.

Can You Proliferate Counters from Infect?

Proliferate was introduced alongside infect as a way to give the mechanic more “reach.” The reminder text of proliferate even mentions players, so you're able to increase the number of counters on them.

What If a Creature Gains Infect Twice?

Unfortunately, multiple instances of infect doesn't do anything. As per 702.90f, they're redundant and change nothing. This is one of the edge cases where poisonous is slightly better since you can have multiple instances of poisonous triggers that stack.

Is Infect a Replacement Effect?

Nothing about infect is an actual replacement effect, though you'd think it is. It's a weird limbo of replacing how damage is dealt, but not as a replacement effect. Damage is basically dealt in different ways to different things. Infect just treats these things differently.

Is Infect Good in Commander?

One of the common gripes about infect is that the hard limit of ten counters isn’t any different for Commander rules, meaning that the game can be incredibly short. Why bother dealing 40 damage or 21 commander damage when I can just hit you for 10 and call it a day?

But since Commander's Rule 0 is a pinnacle of the format, it's always best to talk to your group about it. Some groups may not care while others may have banned specific cards or something else entirely.

How Much Infect Damage Is Needed To Win in Commander?

You need to deal 10 infect damage to a player to kill them in Commander. The Commander Rules Committee has stated that this is because it is very hard to kill more than a single player with poison, especially because your opponents likely are not piling on with their own infect creatures.

What’s the Best Commander for Infect?

You've got a pretty healthy variety of options for infect-based commanders. Atraxa, Praetors' Voice gives you keyword soup and a free proliferate every turn while Skithiryx, the Blight Dragon offers a hasty infect outlet in the command zone.

But I’d also like to mention Saskia the Unyielding. Not only is it in black and green for most infect cards, but it also adds more poison counters with its triggered ability. This means you can rack up poison counters fast and on multiple targets at the cost of being a big target at the table.

Can You Remove Infect Counters?

One of Mark Rosewater's intentional design points for infect was that poisonous counters should not be removable. It was a major upset for Rosewater when Leeches was printed in Homelands. There are some cards that can remove counters from opponents, but none that can remove them from yourself.

Does Infect Trigger Monarch?

Strangely enough, yes. While there’s no actual loss of life from combat damage this way, it’s still treated as damage but no life is lost. The player still gains the monarch token after the damage is dealt, even though life totals didn't change.

How to Beat Infect

Infect's biggest weakness is that it's solely tied to creatures. The best way to stay ahead of an infect player is to make sure their creatures never stay on the board or never connect. Very few infect creatures have evasion so you just need to make sure you can keep them at bay.

The only other way is to play Solemnity, which prevents any counters from being placed on players. You can also play Melira, Sylvok Outcast as a major hose to any infect deck.

Infect Card Gallery

Best Infect Cards

Blighted Agent

A staple card in x infect decks, Blighted Agent is a cheap unblockable threat that already has infect. Thousands of players have lived and died based on this simple 1-drop 1/1.

Blightsteel Colossus

When in doubt, Polymorph this guy out. Not only is Blightsteel Colossus a beast in Polymorph-based decks, but it also prevents being milled out. It’s also just a huge beater that's very, very hard to get rid of.

Grafted Exoskeleton + Phyresis + Tainted Strike

Some of the evilest cards in casual Commander tables, but not worthy of getting independent mentions. Why bother with an infect creature when you can give any creature infect at any time? Grafted Exoskeleton, Phyresis, and Tainted Strike also pair very well with direct damage spells like Chandra's Ignition.

Phyrexian Unlife

Unlike most cards here that give infect to kill other players, Phyrexian Unlife actively prevents you from dying to anything but infect. It's a common combo piece in the old modern Ad Nauseam decks since the loss of life doesn't trigger the card’s second ability.

Triumph of the Hordes

Why bother playing Overrun when you can kill a whole table for less? Triumph of the Hordes is a consistent beast in Commander decks that need an easy out that isn't just Craterhoof Behemoth.

Simic Infect Deck in Modern

Glistener Elf | Illustration by Steve Argyle

This is MTGO user JulianJohn's 5-0 Modern League Simic () infect deck.

This version of infect speeds the game along by using Venerated Rotpriest to pile on poison counters without attacking. Blue is great for ensuring your infect creatures like Blighted Agent get their full pumped-up damage in and Royal Treatment is a cheap way to boost and protect your attackers. The infect staple, Scale Up provides wins in a hurry, and a few counterspells make sure your win condition is the only one that sees the table.

Closing Up the Wounds

Blighted Agent | Illustration by Anthony Francisco

All in all, infect has a lot of problems around its design. Mark Rosewater has mentioned it sits at about a 7 on the Storm Scale, which means that it's unlikely it'll return even if it's not impossible.

I don't like game mechanics that you can't interact with and infect is actively intended to not be interacted with. It also makes the game slightly more complicated and stressful when you have to worry about a secondary life total.

How do you feel about infect cards? Are you for or against the Phyrexian invasion? Let us know in the comments or tell us about it on Draftsim's Discord.

I've gotta gear up. I'm working on a new Hapatra, Vizier of Poisons deck and I've gotta see whether or not I need to include some infect cards. Have a good one!