Glissa's Retriever
Creature — Phyrexian Beast
Haste, toxic 3 (Players dealt combat damage by this creature also get three poison counters.)
This creature can't be blocked by creatures with power 2 or less.
Corrupted — When this creature dies, exile it. When you do, return up to X target cards from your graveyard to your hand, where X is the number of opponents who have three or more poison counters.
Josu Hernaiz
Rulings
Multiple instances of toxic are cumulative. For example, if a creature has toxic 2 and gains toxic 1 due to another effect, combat damage that creature deals to a player will cause that player to get 3 poison counters.
(wotc • 2023-02-04)
After Glissa's Retriever has become blocked by a creature with power 3 or greater, reducing the blocking creature's power won't cause Glissa's Retriever to become unblocked.
(wotc • 2023-02-04)
Toxic doesn't change the amount of combat damage a creature deals. For example, if a 2/2 creature with toxic 1 deals combat damage to a player, that creature will deal 2 damage. The results of that damage are the player loses 2 life and gets a poison counter.
(wotc • 2023-02-04)
If a creature with toxic deals combat damage to a creature or planeswalker, or if it deals noncombat damage, toxic has no effect and no player gets poison counters.
(wotc • 2023-02-04)
You don't choose a target for Glissa's Retriever's last ability at the time it triggers. Instead, a second "reflexive" ability triggers when you exile it. You choose a target for that ability as it goes on the stack. Each player may respond to this triggered ability as normal.
(wotc • 2023-02-04)
Damage dealt by a creature with toxic grants the same number of counters regardless of how much damage is dealt. Notably, if a replacement effect modifies the damage in some way (such as that of Gratuitous Violence), the number of counters given remains unchanged.
(wotc • 2023-02-04)
A player with ten or more poison counters loses the game. This is a state-based action and doesn't use the stack. In other words, it happens immediately and players can't respond to it, just like a player losing the game due to having 0 or less life.
(wotc • 2023-02-04)
Conversely, replacement effects that apply to the number of counters put on a player can modify the counters placed this way. For example, Vorinclex, Monstrous Raider's last two abilities can apply to counters placed this way.
(wotc • 2023-02-04)
Any other effects of that damage, such as life gain from lifelink, still apply.
(wotc • 2023-02-04)
Rulings
Multiple instances of toxic are cumulative. For example, if a creature has toxic 2 and gains toxic 1 due to another effect, combat damage that creature deals to a player will cause that player to get 3 poison counters.
(wotc • 2023-02-04)
After Glissa's Retriever has become blocked by a creature with power 3 or greater, reducing the blocking creature's power won't cause Glissa's Retriever to become unblocked.
(wotc • 2023-02-04)
Toxic doesn't change the amount of combat damage a creature deals. For example, if a 2/2 creature with toxic 1 deals combat damage to a player, that creature will deal 2 damage. The results of that damage are the player loses 2 life and gets a poison counter.
(wotc • 2023-02-04)
If a creature with toxic deals combat damage to a creature or planeswalker, or if it deals noncombat damage, toxic has no effect and no player gets poison counters.
(wotc • 2023-02-04)
You don't choose a target for Glissa's Retriever's last ability at the time it triggers. Instead, a second "reflexive" ability triggers when you exile it. You choose a target for that ability as it goes on the stack. Each player may respond to this triggered ability as normal.
(wotc • 2023-02-04)
Damage dealt by a creature with toxic grants the same number of counters regardless of how much damage is dealt. Notably, if a replacement effect modifies the damage in some way (such as that of Gratuitous Violence), the number of counters given remains unchanged.
(wotc • 2023-02-04)
A player with ten or more poison counters loses the game. This is a state-based action and doesn't use the stack. In other words, it happens immediately and players can't respond to it, just like a player losing the game due to having 0 or less life.
(wotc • 2023-02-04)
Conversely, replacement effects that apply to the number of counters put on a player can modify the counters placed this way. For example, Vorinclex, Monstrous Raider's last two abilities can apply to counters placed this way.
(wotc • 2023-02-04)
Any other effects of that damage, such as life gain from lifelink, still apply.
(wotc • 2023-02-04)