The Magma Cannon is fired using the usual procedure for firing a cannon as provided in the Warhammer rulebook, except that instead of rolling to 'Bounce' the shot, instead place the teardrop-shaped template with the narrow end positioned where the shot landed and the wide end placed straight ahead in the direction of fire. A Misfire result means the weapon does not fire. Roll on the Black Powder Misfire Chart to determine what happens next.