Cloudkill

Most board wipes fix their own size: Damnation kills everything, Toxic Deluge scales with the life you pay, Languish shrinks the number to a fixed four. This one hands the dial to your command zone. The sweep equals the greatest mana value of a commander you own, which turns a static sorcery into a knob you set at deckbuilding rather than a value read off the board. Build around a small commander and it clears tokens; build around an eight-drop general and the -X/-X grows large enough to shrink nearly any creature on the table out of existence. That coupling is the whole design idea, and it is a genuinely unusual place to put a scaling variable: the number comes from your own commander rather than from the opposing creatures the sweep is aimed at, even though the command zone is public information the whole table can read. Because it subtracts toughness rather than dealing damage, the effect walks straight past indestructible, which the fattest commanders in the format often lean on. It rewards the same commander choice you already made for other reasons, then quietly asks whether your general is expensive enough to be worth a second look. The trade-off is honest: point it at a cheap commander and it underperforms, so it only pays off in shells already committed to a heavy top end, where the borrowed mana value is large and reliable.