How to make a unit attack damage in a line and can attack ground?

[Magoiche]

see the title.
I tried to put Artillery (Line) but the damage wont go in a line =X
It only damages the units in the aoe =X

 

[X-maul]

well i see no other way, than doing it with triggers, create an dummy unit, then add expiring timer, and add an spell, like "Crushing Wawe" then order the dummy to use it cast the spell...