She-Hulk, Attorney-at-Law

Most +1/+1 counter payoffs add on a linear curve: a lord here, an anthem there, one counter per attack. This one bends the whole board onto a multiplicative one, taking every counter already sitting on your team and doubling it in a single detonation. The design gates that reach behind a once-per-game clause: the ability fires exactly one time, so it rewards patience over reflex. Pop it with three counters scattered across your creatures and you nudge the board; hold until the field is loaded and the same activation vaults you past the point of recovery. What makes it castable off the top is the self-referential discount: cast her the turn the payoff matters and the ask shrinks by her own mana cost, letting the explosion happen the turn she lands rather than the turn after. Vigilance keeps her swinging into the doubled math without surrendering the block, which matters most on the turn your army has just gotten twice as large and the opponent is hunting for a hole to swing back through. The engine asks you to accumulate before you fire, not grind incrementally, and the green-white pairing points the shell squarely at go-wide creatures and counter accumulation: exactly the board state that turns one doubling into a lethal overrun.