HexZyle
Boar
I don't know how to reproduce the bug, but it happens upon death and can stick around for a bit, even after being revived. This bug is not exclusive to the flying fortress. This bug also occurred when we were fighting high-horse jerk after he nicks your thingymabob. It is client-side only.
The character who this happens to has the three fire skills, (and uses the silver charge flamethrower a lot) and the shadow clone skill.