Feral Animist

The math here is the entire pitch: pay three mana to double the creature's current power, then pay again to double that, and again, until your mana runs out. Each activation reads the power after the previous one resolved, so the sequence is exponential rather than additive: two becomes four, four becomes eight, eight becomes sixteen, and a swing that connects ends most games on the spot. The body itself, a fragile 2/1, is almost incidental; it exists to be the seed value, and the whole apparatus is a mana sink that converts a flooded board into a one-shot kill. The catch that keeps it from breaking anything is that the boost is +X/+0 and lasts only until end of turn, so the doubling buys raw damage, not survivability: the creature stays exactly as easy to kill, and a single removal spell at instant speed wipes out every mana you poured in. It also offers no evasion, which means the payoff lives or dies on whether the attack lands, putting the whole investment at the mercy of a chump blocker. This is the kind of repeatable, self-referential pump that designers tend to print rarely, because exponential scaling is easy to misjudge and ugly to balance; tying it to a creature that any answer trades down on is how the line gets to exist at all.