in a straight line similiar to scarface. i thought of making it a reflection first but thought piercing is better.
The other way it could maybe work is to have it be a time based cooldown. My thinking for that is that it would always be ready when the next wave comes. Maybe something like every 10 (-0.1 per level). So straight line for the whole lane and not just range 2? It sounds too powerful, but scarface isn't being abused right now, so it's probably fine, right?