Creeperhulk

A repeatable Overrun stapled to a body, and that distinction is the whole pitch. Where the classic green alpha-strike anthem is a one-time sorcery that floods the whole team, this prices its boost per creature and per activation: feed it the mana and any one of your attackers becomes a 5/5 trampler for the turn, then another, then another, for as long as you can pay the toll. The base-power-and-toughness clause is the wrinkle worth knowing, because it cuts both ways: it sets a creature to 5/5 rather than adding to it, so it turns a 1/1 mana dork into a real threat but actually shrinks anything already bigger than 5/5 before other modifiers stack on top. That makes it a leveler, not a pure pump, ideal for a board of small Plant tokens or utility one-drops you would rather not see chump-block away. The 5/5 trample frame on the card itself means it pays its own activation, big enough to matter before you spend a single point of mana animating the rest. It is a mana sink in green's oldest tradition: turn excess lands into lethal. The catch is that each activation goes on the stack and targets, so an opponent holding instant-speed removal can answer the pumped creature in response, fizzling the boost and the mana behind it.