Booby trap flour explosion

[Anthony]

Originally Posted by Donny Brook

Something I'm just now wondering about -- how do you handle concussive damage for targets that are inside the origination envelope of the blast?

Any fuel that is further away from the center of the blast than the target is has no effect on the target (unless it gets reflected back towards them by something). A cloud that fills the entire room will do a lot more damage to the building than a cloud only large enough to envelop the PCs, but won't do any more damage to the PCs.