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.
Grateful Apparition
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.
An ability that triggers "Whenever you proliferate" triggers even if you chose no permanents or players while doing so.
Magic: The Gathering · ™ & © Wizards of the Coast · Illus. Umiu Geso
Card data via Scryfall. Rarix is fan-made; not endorsed by the rights holders.
