Core Prowler
Artifact Creature — Phyrexian Horror
When this creature dies, proliferate. (Choose any number of permanents and/or players, then give each another counter of each kind already there.)
Legal in
Modern, Legacy, Vintage, Commander
Rulings (6)
You don't have to choose every permanent or player that has a counter, only the ones you want to add another counter to. Since "any number" includes zero, you don't have to choose any permanents at all, and you don't have to choose any players at all.
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
If a permanent ever has both +1/+1 counters and -1/-1 counters on it at the same time, they're removed in pairs as a state-based action so that the permanent has only one of those kinds of counters on it.
2023-02-04
An ability that triggers "Whenever you proliferate" triggers even if you chose no permanents or players while doing so.
2023-02-04