
All creatures get -X/-X until end of turn, where X is the greatest mana value of a commander you own on the battlefield or in the command zone.
As the acrid fumes drifted through the Lower City, even the vermin ceased to stir.
Illustrated by David Szabo · Commander Legends: Battle for Baldur's Gate · #121
2022-06-10
If your commander is under the control of another player as Cloudkill resolves, it is still on the battlefield and will still be used to determine the value of X.