You wind up a powerful shot, which deals 800% weapon damage to the target and 400% weapon damage to all enemies in between you and the target.
Enemies hit by Powershot are also knocked back.
Powershot is a hunter talent available at level 90.
Patch 5.2.0 (5-Mar-2013): Targeting for Glaive Toss and Powershot has been improved. These abilities will now always hit the primary target and are much more responsive about which secondary targets they hit.; Powershot now cancels Camouflage when the cast begins.