The special effect gives a chance (regardless of the Proc Coefficient) on attack to fire flaming bolt together with the normal missile, which deals 100% damage as Fire. It has a very small (1 yard) blast range, so hitting more than one target with the Demon Machine bolt is problematic.
Stats (Level 8)Edit
"All maddening angles and gnashing gears. These crossbows! How do they work?!" — Sergeant at Arms Carlavoie