[Spell] Need ideas for a visual effect on an ability

[iSkyi]

Hello! I've been using carrion swarm when I need to send missiles, but I really want a way to send a missile a variable distance. With carrion swarm I have to fix the distance in the ability data. Basically what I want would be identical to a ground target attack (like mortar team) but from a dummy unit. Is this a thing? Anyone have any good ways of doing this?