Basically some of the options for FX that the GM can place down when it is added):

1. Artillery explosions (from mortars to artillery cannon fire, either singular or a zone which can drop a set amount or infinite, and with a set interval between strikes, and can be toggled if they are just an effect, or can kill people hit by the explosions).
2. Smoke clouds (from either smoke grenades, and as an option for artillery in option 1).
3. Tracer fire, either directed towards a ground target or randomly into the air.
4. Flak bursts for the air.
5. Sound placement, so in an area you can set that an alarm went off, or hear far-off fighting.