The goal of the Ori is the conquest of the Milky Way Galaxy and the destruction of the Ancients. As the Priors entered the galaxy, numerous worlds fell to their powers. Some accepted Origin, others were destroyed by plagues, infestations, and natural disasters. However, the Priors were only the first wave, as the Ori and their followers prepared for the holy crusade of ships and warriors that was to follow. As the imminent invasion approached, the Priors warned of the impending Doomsday, when all shall witness the final battle between the light and darkness. Also referred to as the Day of Reckoning, a day when all who have renounced the Ori will feel their wrath, the holy crusade began with the arrival through the supergate of four Ori ships in the Milky Way Galaxy.