Piercing shot is one of the few penetrating skills a bow type scout has and is also very handing in fighting things like chimeras and giants because of its knockback ability. The hit box is huge for this particular skill, although the startup is very slow and the pw consumption is huge (76 pw). This means that this skill is usually unspammable except when at the back of a battlefront and you're able to crouch in the midst of battle. I usually use this skill to throw off pursuing enemies and knocking giants, wraiths, and chimeras off cliffs or merely backwards.