Stormsplitter

The math on this Otter is deceptive because the tokens are casters too. Each copy enters with haste and carries the same trigger, so the first spell you cast after it lands makes a copy, and that copy is on the battlefield when you cast the next spell, spawning another off that one. The doubling is not additive; it is multiplicative across a single turn's worth of instants and sorceries. Notice the 1/4 body: four toughness survives most incidental sweeper edges and combat, but one power means the payoff has to come from the token count, not the printed swing. This creature was never meant to attack fairly. What the end-step exile clause pays for is the ceiling. Every copy vanishes when the turn ends, so the whole engine is a one-turn burst that has to convert before it evaporates: a spellslinger's answer to the question of how you close a game in a single wide attack rather than grinding. Haste on both the original and the copies is what makes that window usable at all, since a body that could not attack the turn it multiplied would be a puzzle with no payoff. Plenty of "cast this, get value" spell-count creatures reward each cast with a token or a trigger; this one rewards it with another copy of the reward engine, which is why the numbers run away from you so fast.