Tainted Observer
Creature — Phyrexian Bird
Toxic 1 (Players dealt combat damage by this creature also get a poison counter.)
Whenever another creature you control enters, you may pay . If you do, proliferate. (Choose any number of permanents and/or players, then give each another counter of each kind already there.)
Legal in
Pioneer, Modern, Legacy, Vintage, Commander, Brawl, Historic
Rulings (13)
An ability that triggers "Whenever you proliferate" triggers even if you chose no permanents or players while doing so.
2023-02-04
To proliferate, you can choose any permanent that has a counter, including ones controlled by opponents. You can choose any player who has a counter, including opponents. You can't choose cards in any zone other than the battlefield, even if they have counters on them.
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.
2023-02-04
Players can respond to a spell or ability whose effect includes proliferating. Once that spell or ability starts to resolve, however, and its controller chooses which permanents and players will get new counters, it's too late for anyone to respond.
2023-02-04