Sacramental firewall

The sacramental firewall is a firewall that the Preacherbot gave to Fry to ward off Bender's ghost. The firewall wards off all ghostware within 20 feet. However, it is possible for a ghost to come through the 20 foot radius to the firewall itself. Apparently, after a robot ghost takes over the software of the firewall, it can be used to make projections. Bender used the firewall for this purpose to make a projection of himself on a wall and give Fry a heart attack. However, he survived the heart attack.