Players cannot increase a numeric attribute by a negative amount. If an effect would instruct a player to do so, they increase it by 0 instead. Example: A player plays Last Stand, which reads “Double a friendly unit's Might this turn. Give it Temporary.” The player declares a 2 [M] unit as the target during finalization. In reaction to Last Stand, an opponent plays Eclipse targeting the 2 [M] unit. When Last Stand resolves, the unit is -2 [M]. Last Stand instructs its controller to increase the unit’s Might by its current amount, -2, when the double action is performed. This is not possible, so the unit’s Might is increased by 0 instead.
