Blackwing - Sirocco the Dawn (Green) [DL17-EN007] Rare

If your opponent controls a monster and you control no monsters, you can Normal Summon/Set this card without Tributing. Once per turn: You can target 1 "Blackwing" monster you control; until the End Phase, it gains ATK equal to the total ATK of all "Blackwing" monsters currently on the field, except itself. Monster other than the targeted monster cannot attack during the turn you activate this effect.