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.
An ability that triggers "Whenever you proliferate" triggers even if you chose no permanents or players while doing so.
If a player or permanent has more than one kind of counter on it, and you choose for it to get additional counters, it must get one of each kind of counter it already has. You can't have it get just one kind of counter it already has and not the others.
This printing is one of 2 catalogued treatments from AJMP — the lineup includes Nonfoil alongside the standard finish. Across our catalog the Rarix library tracks every variant in the same family so collectors can compare price, scarcity and demand inside a single lineage.
Card #173 of *Jumpstart Arena Exclusives*, the set that shipped alongside the July 2020 Jumpstart Arena Exclusives release.
Card type: Creature — Elf Druid, color identity green, printed at common. Commons fill the bulk of a booster pack's volume. Mana cost: {1}{G} (2 converted). Keyword abilities: Proliferate.
Legal across the major constructed formats — Modern, Legacy, Vintage, and Commander — plus Standard rotation play.
EDHrec ranks this card #5,312 in Commander, putting it in the niche-pick tier of the format's playable pool.
Illustrated by Matt Stewart. Rarix catalogs 988 other cards credited to this artist.
Magic: The Gathering · ™ & © Wizards of the Coast · Illus. Matt Stewart
Card data via Scryfall. Rarix is fan-made; not endorsed by the rights holders.
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.
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.
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.
You may choose Pollenbright Druid as the target of its own ability.
