How many poison counters does it take to lose in MTG?

A player loses the game as soon as they have ten or more poison counters. In Two-Headed Giant, the threshold is fifteen poison counters for the team. Poison counters are permanent — there are very few ways to remove them — so every one counts.

Does infect damage reduce life totals?

No. Damage from an infect source never causes life loss. Instead, it converts entirely into poison counters on players or -1/-1 counters on creatures. Your life total is unaffected by infect damage.

Can you remove poison counters in MTG?

Almost never — there are very few cards in Magic's history that remove poison counters, and none are commonly played. You should generally treat every poison counter as permanent when deciding how aggressively to trade against an infect strategy.

What formats is infect legal in?

Infect cards are legal in any format where the specific cards are permitted — most infect cards from Scars of Mirrodin block are legal in Modern, Legacy, Vintage, and Commander. Individual cards may be restricted or banned depending on the format. Check current ban lists, as the competitive landscape changes regularly.

Does infect work if the creature is destroyed before damage is dealt?

The game uses the last known information of the source when damage is dealt. If an infect creature is destroyed in response to an ability that would cause it to deal damage, and the damage still resolves, the infect rules still apply — the counters go on as if the creature still had infect.

What is the difference between infect and wither?

Both abilities convert damage dealt to creatures into -1/-1 counters. The key difference is that infect also converts damage dealt to *players* into poison counters, while wither has no effect on players beyond normal damage. Infect effectively combines wither's creature-damage conversion with the poison-counter delivery that older mechanics like poisonous handled separately.

Infect: MTG Mechanic Explained

Ten poison counters and you're out. That's the whole promise of infect - and it's why the mechanic has fascinated and frustrated players in equal measure since it arrived in Scars of Mirrodin in 2010.

Infect changes the currency of combat. Instead of chipping away at a player's life total, an infect source drops poison counters on players and -1/-1 counters on creatures. It's a parallel win condition running on a completely different track, and that asymmetry is what makes it so disorienting to play against - and so satisfying to pilot.

What is Infect?

Infect is a keyword ability that changes how damage is dealt by the source carrying it. A creature or spell with infect doesn't cause life loss when it damages players, and it doesn't leave damage markers on creatures. Instead:

Damage to players becomes poison counters on those players.
Damage to creatures becomes -1/-1 counters on those creatures.

Any player who accumulates ten or more poison counters loses the game immediately. In Two-Headed Giant, that threshold rises to fifteen counters for the team.

Think of it like a second health bar that only infect sources can attack. A player sitting at 20 life is completely safe from an infect creature in one sense - and completely doomed in another, if they let enough poison counters stack up.

Thematically, infect is Phyrexian through and through. Every creature with infect and every card that meaningfully supported the mechanic was printed with a Phyrexian watermark. It's the corruption of Phyrexia made mechanical: not killing you outright, but infecting and degrading you over time.

Infect rules

The official comprehensive rules (November 14, 2025 - Edge of Eternities) cover infect under rule 702.90. Here's what each part means in practice.

Infect is a static ability

It's always on. You don't activate it, you don't pay for it - the moment a source with infect deals damage, the conversion from damage to counters happens automatically.

Damage to players becomes poison counters

"Damage dealt to a player by a source with infect doesn't cause that player to lose life. Rather, it causes that source's controller to give the player that many poison counters." - CR 702.90b

This is the core rule. If an infect creature deals 3 damage to you, you don't lose 3 life. You get 3 poison counters. Your life total is untouched.

Damage to creatures becomes -1/-1 counters

"Damage dealt to a creature by a source with infect isn't marked on that creature. Rather, it causes that source's controller to put that many -1/-1 counters on that creature." - CR 702.90c

This is infect's hidden power in combat. Normal damage is cleaned up at end of turn; -1/-1 counters are permanent. Block a 3/3 infect creature with your 4/4, and your creature survives with three -1/-1 counters on it - now a 1/1. That's a very different outcome from a normal trade.

Rules note: This also means infect combines powerfully with wither, which operates on the same -1/-1 counter principle for creature damage (though wither doesn't affect players). Having both on the same creature is redundant - the counters are applied once regardless.

Zone and last-known-information rules

Two edge cases worth knowing:

If a source with infect leaves the battlefield or changes zones before its damage resolves, the game uses its last known information to determine whether it had infect. So if your infect creature is destroyed in response to a damage-dealing ability it activated, the damage it would deal still applies as poison counters or -1/-1 counters.
The infect rules apply regardless of what zone the source is dealing damage from. This isn't often relevant, but it means infect functions consistently even in unusual rules situations.

Multiple instances are redundant

Giving an infect creature infect again doesn't stack or double anything. The second instance does nothing.

Common misunderstandings

"I took infect damage, so my life total went down." - Nope. Infect damage never reduces life totals. You gained poison counters, which is a separate track entirely.

"Gaining life cancels out poison counters." - It doesn't. Life gain has no interaction with poison counters whatsoever. Sitting at 40 life doesn't make you safer against infect; you still lose at ten counters.

"Infect and wither stack on a creature." - They don't. Both abilities convert creature damage to -1/-1 counters; a creature with both abilities applies the counters once, not twice.

"I can destroy an infect creature before it deals damage to stop the poison." - Mostly no. Damage is dealt simultaneously with destruction in many cases, and if the infect source had the ability when damage was assigned, the counters still go on.

Strategy

Playing with infect

The fundamental advantage of infect is that it operates on a 10-point clock rather than a 20-point clock. An infect creature that deals 4 damage a turn wins in three swings; a non-infect creature doing the same needs five. That compressed timeline shapes everything about how infect decks are built.

Infect decks historically want to do two things at once: make one creature very large, very quickly, and protect it through a single decisive turn. That's why pump spells - cards that give +power and +toughness until end of turn - are so central to the archetype. A 1/1 infect creature with four pump spells is a ten-poison-counter kill in one combat step.

Tainted Strike deserves a special mention here. A one-mana instant that grants infect until end of turn means any creature on your side of the board can become a poison delivery system, and it can be held up as a combat trick your opponent won't see coming.

Key considerations when building with infect:

Prioritise evasion (flying, unblockable, trample) so your infect creatures connect reliably.
Instant-speed protection spells (hexproof, indestructible) let you force through the kill on your opponent's turn as well as your own.
Proliferate is infect's natural companion - it spreads poison counters already on players without needing to deal combat damage again.
One infect creature and eight pump spells can win a game; you don't need many threats.

Playing against infect

The most important mental shift when facing infect is reassessing what's dangerous. A 1/1 infect creature that your opponent is carefully protecting is a kill threat. A 5/5 non-infect creature is not on their poison plan at all.

Kill infect creatures immediately and efficiently. Letting one sit on the table gives your opponent time to assemble pump spells.
Don't block infect creatures casually. The -1/-1 counters persist; you may win the trade by toughness but leave your creature functionally destroyed.
Removing poison counters is extremely rare in Magic - there are very few ways to do it. Don't assume you can recover; play as though every poison counter is permanent.
Be aware of Tainted Strike and similar grants. An opponent passing priority with mana up against an infect deck may be setting up a lethal pump sequence.

Notable cards

Inkmoth Nexus is one of the most iconic infect enablers ever printed - a land that becomes a 1/1 flying infect creature for '{1}'. It's almost impossible to interact with before the turn you activate it, it provides mana when you're not using it as an attacker, and it dodges sorcery-speed removal. In Modern infect decks, it does an enormous amount of work.

Phyresis ({1}{B}) is a simple aura that gives any creature infect, extending the mechanic to whatever you want to deliver poison with. It's the cleanest expression of the "grant infect" design space.

Tainted Strike ({B}) gives a creature +1/+0 and infect until end of turn for a single black mana. The low cost and instant speed make it a genuine combat trick and finisher in one card.

Hand of the Praetors functions as a lord for infect creatures, giving all other creatures with infect +1/+1 - the only card in the game specifically designed to pump the infect team as a type.

Contagion Engine ({6}) doesn't have infect itself, but it proliferates twice with a single activated ability. In an infect-adjacent strategy, this turns a handful of poison counters into a lethal total with one use.

Spread the Sickness ({4}{B}) destroys a creature and then proliferates. Removal plus poison escalation on one card is exactly the kind of card an infect deck wants in longer games.

Infectious Bite ({1}{G}) has an interesting design: it has a creature deal damage equal to its power to another creature - and each opponent gets a poison counter. It doesn't say the creature needs infect, which makes it a flexible way to inject poison counters while also handling a blocker.

History and evolution of Infect

Infect arrived in Scars of Mirrodin (SOM) in 2010, a set that leaned hard into the Phyrexian invasion of Mirrodin. It was designed as a fusion of two earlier mechanics: wither (which converted creature damage to -1/-1 counters, from Shadowmoor in 2008) and poisonous (which added poison counters as a triggered ability, from Future Sight in 2007 and Lorwyn in 2007). Infect collapsed both effects into a single cleaner keyword.

The mechanic was featured on the rules card in all three sets of the Scars block:

Scars of Mirrodin - rules card 1 of 5
Mirrodin Besieged (MBS)** - rules card 4 of 5, where infect expanded into white
New Phyrexia (NPH)** - rules card 3 of 4, where it finally reached red

By the end of the Scars block, infect had touched all five colours, though it remains most at home in black and green, with a natural secondary presence on artifacts.

When Phyrexia: All Will Be One (ONE)** released in 2023 - the return to Phyrexia after more than a decade - many players expected infect to come back. R&D considered it, but ultimately chose not to include it. The stated reasons were twofold: a general sour feeling in design toward environments built around -1/-1 counters, and the recognition that infect is divisive among players. It's one of the more polarising mechanics in the game's history, genuinely beloved by the players who enjoy racing on a compressed clock and genuinely disliked by players who find it a frustrating way to lose.

Infect does have a small, self-aware cameo in Unfinity through stickers - the silver-bordered set's way of poking fun at mechanics too strange or powerful to reprint in black-border sets.

Whether infect returns in a future Phyrexia-themed set remains to be seen. For now, it occupies a special place in Magic history: a mechanic so thematically resonant and mechanically elegant that it's hard to imagine the Scars block without it, and yet one the game has very deliberately stepped back from.