Sounds like an fps nightmare.
That. But if you take a look at the following idea, this might be quite limited compared to other maps.
What about a volcanic area instead that has volcanic rock formations that are some still glowing but the volcano itself spewing out a black cloud similar to tar?
That wouldn't add fire to it but similar to the sandclouds of dunes the black tar cloud would limit visibility and do some damage if you fly through it?
It could be something that got active due to the war and been dormant for centuries.
Many small volcano-mountain-things that randomly throw out those black tar clouds in a rocky mountainside with dark surroundings and sometimes glowing lavaseas ... Sounds lovely! If you'd limit the amount of clouds for a higher amount of randomly thrown out tar clouds you'd get the fps-problem under control - and introduce rugged, high mountains to limit visibility.
By the way - what about some forrest maps?