Subaqueous Unrest

When Subaqueous Unrest enters the battlefield, create X 0/1 Merfolk Warrior creature tokens.
Merfolk creatures you control get +1/+0 as long as they are attacking.
Enraged by the Easterners who have invaded their home, the merfolk of Flint attack Eastern boats that cross the Upper and Lower Flint Bays, and craftily cut away at the supports of Torq's Bridge, knowing that the collapse of the bridge could cripple the colonies' trade.