Condemn is a keyword in Artifact.
A condemned entity is instantly destroyed. Only entities present on the board (i.e. units, improvements, and items equipped to heroes) can be condemned. Condemning a unit awards the appropriate amount of gold to the opposing player as if that player had killed it through combat or other means. Units can only avoid dying to a condemn effect if they have a Death Shield -- other effects like Damage Immunity and Armor are irrelevant.