Proliferate

Proliferate effects look at every permanent and player with a counter on them and add another of each kind already there. This covers dedicated proliferate engines like Atraxa, Praetors' Voice, Inexorable Tide, Karn's Bastion, and Contagion Engine, plus trigger-based spreaders like Evolution Sage and Thrummingbird. Proliferate scales +1/+1 counters, loyalty, charge, poison, -1/-1, and any other counter type already present. Distinct from counters.counter_placer, which puts fresh counters on permanents from nothing, and from counters.counter_doubler, which amplifies counters as they enter rather than spreading existing ones. Also separate from counters.counter_mover, which relocates counters between permanents instead of generating new ones.