Have the ability start a create persistent effect with
- target location: caster point
- period count: 1
- period offset: x = 0, y = negative [range]
- period duration: 0
- period effect: your launch effect
This will make one launch effect, targeting the caster's location, offset by the range you put into period offset.
If needed: You can change the orientation of the shot by modifying Location Offset Start and Location Offset End. The line you can draw between these locations dictates the orientation of the period offset.