Unit needs to be created in front of other unit

Hello,

I want a hero to be able to use an ability that creates a special effect (Unit) that is like a ray that is launched.

I've been trying to find how to do it, but I don't know how to get it right in every angle. Since the unit is a line it must always face the exact way in relation with the casting unit. How is this done?

Thanks in advance.|||There's a function in the real dropdown list: Facing Angle of Unit.