Full Flowering

The double-X cost is the whole conceit here: populate has almost always ridden along as a single-shot bonus stapled to another effect (a combat trick, a token maker, an anthem), and this strips it down to the mechanic itself before buying the count twice over. Spend six mana above the green pip and you populate three times; every additional pair of generic mana adds another copy. That structure makes it a payoff card rather than an engine card. It never targets, so with an empty board it still resolves and simply does nothing, and off a lone token it barely earns its mana. What it wants is a field already carrying your best creature token: one whose base copiable characteristics justify a triple, whether that is a large body, an enters-the-battlefield trigger worth stacking, or keywords printed onto the token itself. The rules wrinkle to respect is that populate copies only base copiable characteristics, so counters do not come along for the ride; a token that is only large because of a stack of +1/+1 counters produces copies at its printed stats, and a token whose base is 0/0 simply dies on arrival. Populate reads only creature tokens, which sets a hard ceiling: the payoff is entirely dictated by whatever sits on the battlefield when you untap with the mana to make X worthwhile. That board-state gate casts the card as a finisher for a token-copy deck, one of green's few ways to turn a single high-quality token into a small army in one sorcery.