Kalonian Hydra

Doubling is a dangerous verb to hand a creature, and this one earns its rate by binding the trigger to the attack step rather than to entering or to an activated cost. It lands as a 4/4 with trample, a fair body for five mana, and the math stays inert until the swing: nothing happens the turn it resolves. The first attack makes it an 8/8, the second a 16/16, and because the doubling reads "each creature you control," every other counter-bearing body on the board rides the same exponential curve. That clause is what separates it from a vanilla beater: it rewards a battlefield already stocked with +1/+1 counters, collapsing a go-wide board into a single overwhelming combat step. The discipline is all in the timing. Because the trigger needs an attack to fire, the opponent gets one clean window to remove it before the curve starts compounding, and that window is the whole tension of the card: answer it before it attacks, or let the controller's next swing double everything they spent the game building. Trample is the finisher that denies chump blockers their stall, since a 16/16 trampler is unbothered by a single body in front of it. It belongs to green's lineage of "counters matter" threats, the kind that ask for a counter-centric board and then pay it back with a number that gets out of hand a turn faster than the opposing clock expects.