MTG Infect, Toxic, Wither and Extort mechanics guide image showing poison counters, green infect damage, toxic attacks, wither decay, corrupted effects, and extort life drain in a dark Commander battlefield.

MTG Infect, Toxic, Wither & Extort Mechanics Guide

Most Magic: The Gathering damage does one thing: it reduces a life total or marks a creature. These mechanics change what damage does — turning it into poison counters, into -1/-1 counters, or into a slow drain across the whole table.

They also come with an alternate way to lose the game that has nothing to do with life totals, and a set of rules subtleties that decide real games: whether infect is a replacement effect (it is not), whether multiple instances stack (usually not), and exactly when poison ends a game.

This guide covers infect, toxic, wither, poison, corrupted, and extort.

This is the fifth article in our series on advanced MTG mechanics, following our guides to the Eldrazi mechanics, cascade and storm, convoke and delve, and landfall and prowess.

Poison Counters: The Second Way to Lose

Before the mechanics, the win condition they all feed. A player with ten or more poison counters loses the game — immediately, as a state-based action, regardless of their life total. A player at 40 life with ten poison counters loses just as surely as one at 1 life.

Two things to know up front:

  • Poison counters are cumulative and hard to remove. There is very little in the game that takes poison counters off a player, so every one you deal is essentially permanent progress toward the kill.
  • The number changes in one format. In Two-Headed Giant, a team loses at fifteen poison counters instead of ten. Everywhere else, ten is the number.

Infect and toxic are the two main ways to deliver poison counters. They look similar and work very differently.

Infect

Infect (CR 702.90) is a keyword ability that changes what a source's damage does:

  • Damage to players becomes poison counters — that many, instead of losing that much life.
  • Damage to creatures becomes -1/-1 counters — that many, instead of being marked as damage.

So a 5/5 with infect attacking an open opponent gives them five poison counters, not five life loss. Blocked by a normal 3/3, it puts five -1/-1 counters on that 3/3, killing it, while the infect creature takes three normal damage back. If the blocker also had infect or wither, then that return damage would be dealt as -1/-1 counters too.

The Detail Judges Get Asked About: It Is Not a Replacement Effect

It is tempting to think infect "replaces" damage, but the rules are careful here, and it matters. The damage is still dealt — infect changes the result of that damage, not whether damage happens. Several real consequences follow:

  • Lifelink still works. A source with infect and lifelink deals damage, so its controller gains that much life — even though the target got poison counters rather than losing life.
  • "Whenever this deals damage" triggers still fire. Damage was dealt, so damage-triggered abilities trigger normally.
  • Damage prevention still stops it. If the damage is prevented, no damage is dealt, so no poison or -1/-1 counters appear. Protection and fog effects work against infect.

More Infect Rulings

  • It applies to all damage, not just combat. An infect source dealing noncombat damage — a direct-damage ability, say — still deals it as poison or -1/-1 counters.
  • The -1/-1 counters are permanent. They do not wear off at end of turn, and regeneration does not remove them.
  • Multiple instances are redundant. Two copies of infect on one creature do nothing more than one.
  • Poison, not life. An opponent hit by infect loses no life at all — which means it slips past life-gain strategies entirely.

The most extreme infect card in the game is in stock: Blightsteel Colossus, an 11/11 with infect and trample. A single unblocked hit deals eleven poison counters — one more than the ten needed to lose — so connecting once ends the game outright. Skithiryx, the Blight Dragon is the classic infect commander: a hasty, flying, regenerating 4/4 that can close a game in three connections and is very hard to kill in between.

Toxic

Toxic (CR 702.164) is the modern, additive take on poison, and it works completely differently from infect. Written as Toxic N, it means that when this creature deals combat damage to a player, that player gets N poison counters in addition to the normal combat damage.

The differences from infect are the whole point:

  • Toxic does not replace anything. The creature deals its normal combat damage to the player's life total, and then adds N poison counters on top. The opponent loses life and gains poison.
  • Toxic N is independent of power. A 5/1 with toxic 1 deals five damage and one poison counter. Infect ties the poison to power; toxic does not.
  • Toxic values add up. If a creature has toxic 2 and gains toxic 1 from another effect, its total toxic value is 3. Unlike infect, stacking toxic does something.
  • Combat only. Toxic applies only when the creature deals combat damage to a player, not when it deals noncombat damage.

A creature with both infect and toxic delivers poison from both: the infect damage becomes poison counters equal to its power, and the toxic ability adds its N on top.

Wither

Wither is infect's older, gentler half. A source with wither deals damage to creatures in the form of -1/-1 counters — exactly like the creature half of infect — but damage to players is completely normal.

So wither is purely a combat tool against creatures: instead of dealing damage that heals at end of turn, it shrinks the blocker or attacker permanently. It pairs beautifully with -1/-1 counter payoffs, and it is the reason cards that care about creatures dying or shrinking often lean on wither and infect together.

Like infect, wither's -1/-1 counters are permanent, and wither only changes damage to creatures — never to players or planeswalkers.

Corrupted

Corrupted is not a keyword ability — it is an ability word, with no rules meaning of its own, marking cards that get better when an opponent has three or more poison counters.

  • One opponent is enough. In multiplayer, you only need a single opponent at three-plus poison for your corrupted abilities to switch on — not all of them. (Some cards do scale per corrupted opponent; read the card.)
  • When it is checked depends on the card's wording. Corrupted is an ability word, not a single rules engine. A static corrupted ability is on only while the condition holds. An activated ability may check the condition when you activate it. A triggered ability with an "if" condition may need the condition to be true both when it triggers and when it resolves. Always read the full card text.
  • It rewards spreading poison early. Three counters is a low bar, which turns even a small amount of toxic or infect into a real payoff engine.

Extort

Extort (CR 702.101) is the odd one out here — it has nothing to do with poison. It is an Orzhov drain mechanic, and it reads: whenever you cast a spell, you may pay {W/B}; if you do, each opponent loses 1 life and you gain life equal to the total life lost.

The Rulings That Come Up

  • It triggers on every spell you cast. Not just creatures, not just once a turn — every single spell. In a long game that is an enormous amount of incidental drain.
  • Countering your spell doesn't stop it. Extort triggers on cast, so even if your spell is countered, the extort trigger still resolves and you may still pay to drain.
  • The mana is hybrid. {W/B} can be paid with either white or black mana, so it fits comfortably in any deck with either colour.
  • Extort does not add white-black colour identity by itself. The {W/B} symbol appears in reminder text, and reminder text is ignored for Commander colour identity. That is why a card like Crypt Ghast can be played in mono-black Commander decks, even though extort can be paid with either white or black mana.
  • Multiple instances each trigger. Control three permanents with extort, cast one spell, and you get three separate extort triggers — three chances to pay {W/B}, each draining and gaining separately. You may pay each once.
  • You decide when the trigger resolves. You do not commit to paying when you cast the spell; you choose as each extort ability resolves, which means you can hold up the option and only pay if the mana is spare.
  • Life gain scales with life actually lost. You gain equal to the total life opponents actually lost. If an opponent's life can't change, that opponent contributes nothing to your life gain.

The engine cards are in stock. Crypt Ghast has extort and doubles your Swamp mana, which conveniently pays for all those {W/B} triggers, and Blind Obedience is a rare noncreature extort source that also slows the whole table down. Stack a few extort permanents and every spell you cast chips the entire table while refilling your own life.

Quick Reference

Question Answer
How many poison counters lose the game? 10 (15 per team in Two-Headed Giant)
Does infect deal damage to a player as life loss? No — as poison counters instead
Is infect a replacement effect? No — damage is still dealt, only its result changes
Does a source with infect and lifelink gain life? Yes — damage was dealt, so lifelink applies
Do multiple instances of infect stack? No — redundant
Does toxic replace combat damage? No — normal damage plus N poison counters
Do multiple toxic values add up? Yes — total toxic value is the sum
What does wither change? Damage to creatures becomes -1/-1 counters; players take normal damage
What turns on corrupted? One opponent with three or more poison counters
Does extort trigger if my spell is countered? Yes — it triggers on cast

Why These Matter in Commander

Infect is a genuine alternate win — with a warning. Ten poison counters end a player regardless of life, which lets an infect deck sidestep the huge life totals and lifegain that define Commander. But infect is also one of the most disliked mechanics at casual tables precisely because it ignores the life-total game everyone else is playing. It is very much a Rule 0 topic, and Triumph of the Hordes is the reason why: it gives your entire board infect and trample for one turn, turning a normal creature deck into a surprise poison kill that ends multiple players at once.

Toxic is the friendlier poison. Because toxic creatures still deal normal damage and only add a few poison counters, they play a fairer game than infect — you can pressure life totals and inch toward the poison kill at the same time, and proliferate turns those small counter piles into a real second threat.

Corrupted rewards even a light poison splash. You do not need a dedicated poison deck to benefit — a single toxic creature getting an opponent to three counters switches on every corrupted card you have.

Extort scales with the format. Long multiplayer games mean many spells cast and three opponents to drain each time. An extort engine that looks trivial in a duel becomes a table-wide clock and a huge life buffer in Commander.

You can find the pieces for these strategies in our full catalogue, or import your decklist directly with our decklist search tool.

Frequently Asked Questions

How many poison counters make you lose?

Ten in almost every format — it is a state-based action, so a player with ten or more poison counters loses immediately regardless of their life total. The one exception is Two-Headed Giant, where a team loses at fifteen.

Is infect a replacement effect?

No, and this is the detail that catches people. The damage is still dealt; infect only changes what that damage does — poison counters to players, -1/-1 counters to creatures. Because damage is genuinely dealt, a source with infect and lifelink still gains its controller life, and damage-triggered abilities still trigger. Damage prevention, however, stops the counters entirely, because then no damage is dealt.

What's the difference between infect and toxic?

Infect changes what the damage results in: a player gets poison counters equal to the damage dealt instead of losing life, and a creature gets -1/-1 counters instead of marked damage. Toxic adds poison on top of normal combat damage: the player loses life to the creature's power and gains N poison counters. Infect ties poison to damage dealt and multiple instances are redundant; toxic is a fixed number independent of power and does add up across multiple instances.

Do multiple instances of infect stack?

No. Multiple instances of infect on the same creature are redundant. This is a known weakness compared to toxic, where a creature's total toxic value is the sum of all its toxic abilities.

Does wither affect damage to players?

No. Wither only changes damage dealt to creatures, turning it into -1/-1 counters. Damage a wither source deals to players or planeswalkers is completely normal.

What counts as a corrupted opponent?

Any single opponent with three or more poison counters. In multiplayer you only need one such opponent to switch on your corrupted abilities, though a few cards scale their effect for each corrupted opponent — always read the specific card.

Does extort trigger on every spell?

Yes. Extort triggers whenever you cast any spell, of any type. Each permanent you control with extort gives its own trigger, so multiple extort sources multiply the drain. You choose whether to pay {W/B} as each trigger resolves, and even a countered spell still gives you the extort trigger.

Can I remove poison counters from myself?

Very rarely. Only a small number of cards can remove poison counters, so in practice they are close to permanent. That is a large part of what makes poison such a threatening clock — the progress almost never goes backwards.

More guides in our advanced mechanics series:

The keyword abilities series:

Related guides:

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