So, I was finally reading Tales of Mythic Europe, and I fell on this gem on p135: "Hermetic magi have tried to create the fine powder that causes explosions before, but the Finesse required is too high to make it a practical weapon outside a working mill."
I guess this resolves https://forum.atlas-games.com/t/dust-explosions/6583/1, 2 years later. :mrgreen:
CrAu 15
The Burning Fog
R: Sight, D: Dia, T: Ind
Req: Ignem
Creates a fog of inflammable vapor, which smells strongly of alcohol, light oil, and brimstone. If ignited, everything inside the fog takes +15 damage from the fire. The fog is highly flammable and may ignite from any flame or spark, but can be set burning with a small Ignem spell. The fogbank is large enough to engulf a village, even a tightly clustered town. In inhabited areas flames are kept in fire-safe areas, but even in the darkest night most towns have a few small flames burning in fireplaces or at least glowing embers that are perfectly able to start the fog burning. A burning fog starts secondary fires, which progress normally - everything that could be set on fire from the damage will burn and continue until put out or the fuel is consumed.
Normal rain washes the fog out of the air almost immediately; light rain generally suppresses secondary fires. Weaving a burning fog into an existing mist or fog tends to thin the resulting fire - divide the damage by two or more. Wind may blow the fog aside and away, but a light wind will usually fan the flames and spread the resulting fire. The ideal condition is dry, still air.
(Base 3, +3 Sight, +1 Dia, No + for requisite)
I used to work as a performing scientist. Among the demonstrations were small, stage-sized explosions. Dust clouds are difficult to work with- they're hard to get to the right density. Flaming vapors are much easier to create.