Fractal Mascot

A stun counter is Simic's version of tempo you don't have to keep paying for. Older tap-down effects (Frost Breath, Icy Manipulator) rented an opponent's blocker for a single turn; the stun counter buys the second one for free, since the tapped creature spends its next untap step burning the counter instead of coming back online. So the enters-the-battlefield trigger doesn't just clear a lane for a 6/6 trampler as it resolves: it locks that blocker out of the following combat too, which is precisely the window a trample body wants. The counter also lands on the creature rather than on a permanent you control, so it survives the tap-effect's usual weakness of a blink or a bounce resetting the clock; removing the trampler doesn't refund the opponent their untap. What keeps the whole package fair is the six-mana price and the single-target scope: this is a one-creature answer, not a board freeze, and against a wide board it clears exactly one blocker before the trample math has to do the rest. It reads as a finisher that carries its own escort, a beater that arrives having already dealt with the thing most likely to chump it.