Poison, infect & toxic
Core concepts
Ten poison counters and you lose — even in Commander, even at 40 life.
How it works
A player with ten or more poison counters loses the game. It's a state-based action, so it happens immediately and can't be responded to, just like reaching 0 life. Commander doesn't scale it up: it's still ten, against a 40-point life total, which is why poison is a real threat at the table.
Infect means the damage is dealt as -1/-1 counters to creatures and poison counters to players — the player loses no life. Toxic N is gentler: combat damage to a player is dealt normally AND they get N poison counters. Proliferate adds one more poison counter to any player who already has one.
Common confusions
“Is infect damage really damage?”
In every respect. It can be prevented or redirected, lifelink still gains life, and "whenever this deals damage" triggers fire. It just results in counters instead of life loss or marked damage. Planeswalkers lose loyalty normally.
“Does my infect commander still deal commander damage?”
Yes. Combat damage it deals to a player is still damage dealt by your commander, so it counts toward 21 commander damage as well as giving poison counters.
“Does toxic reduce the damage?”
No. A 2/2 with toxic 1 deals 2 damage to the player, who loses 2 life AND gets a poison counter. Toxic only works on combat damage to a player, and multiple instances add up.
“Do the -1/-1 counters go away?”
No. Unlike marked damage, they stay at end of turn, and regeneration doesn't remove them.
Infect & toxic cards
Ranked by how often Commander decks actually play them.
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