Pattern Auto-translated

I want to add the ability for archers to deal 100% damage to the primary target and 50% damage to the target behind it. However, the pattern only defines specific cells, so if the archer is on the other side of the field, the pattern doesn't work correctly. How can I fix this, and is it possible to make the selection of the second target depend on the archer's position? In other words, to make this pattern essentially a limited magical attack.

In general, it would be great if arrows could pierce through enemies, like in Heroes 6. I understand that this can't be done with an activated ability, but at least as a passive skill.