The hellbore cannon was a Hydran heavy weapon, similar to the Federation photon torpedo, with a few differences: the warhead had a force field that activated upon firing. Also, the warhead was likened to a fusion bomb and the effects of the force field caused the fusion explosion to wrap around the entire ship then implode. Due to the nature of deflector shields, this would cause the greatest damage to the weakest shield. In addition, the hellbore cannons suffered from a slower rate of fire when compared to photon torpedoes. (RIS Bouteina: "Hospital Blues")