First Cast: Varus starts drawing back his next shot, gradually increasing its range and damage. Maximum range is achieved in 2 seconds.
While preparing to shoot, Varus cannot autoattack or use his other abilities, and his movement speed is slowed by 20%. After 4 seconds, Piercing Arrow is automatically cancelled, going on full cooldown and refunding half of its mana cost.
Second Cast: Varus fires, dealing physical damage to all enemies in the arrow's path, reduced by 15% per enemy hit (down to a minimum of 33%).