When you deploy this unit, choose one: This unit gets +2 power and +2 health until end of game. Or: This unit gets Double Damage until end of game.
Keywords
Double Damage
Double Damage: An isolated, static ability played during the damage placement POP that means, "Put 1 additional damage counter on the defending unit for each 1 damage that wasn't prevented." Damage counters placed by a unit with Double Damage are in addition to the counters that would be placed normally if the attacking unit did not have Double Damage.