The Great Aerie

Planechase design lives or dies on how a plane rewards commitment, and this one snowballs a board rather than a single threat. Bolster 3 on arrival and again each of your upkeeps piles counters onto whatever creature you control with the least toughness, which quietly patches your smallest bodies before it ever fattens a bomb; the effect chases the weakest link, so a wide board keeps getting harder to sweep as long as you stay planeswalked here. The chaos ability is where the plane bares its teeth: two creatures dealing damage equal to their toughness to each other turns those accumulated counters into a removal engine, since a bolstered blocker with inflated toughness can trade up into an opponent's threat for free. That coupling is the whole idea. The bolster half inflates toughness, and the chaos half spends toughness as a weapon, so every upkeep you spend on this plane compounds toward a fight you win by wide margins. It is a Tarkir plane whose flavor (a mountain aerie breeding ever-larger fliers) maps cleanly onto its function, and it belongs to the small class of Planechase cards built to be actively hostile to leave: walking away surrenders both the counter drip and the coin-flip payoff you have been stacking counters to enable.