"Since our earliest stories, every millennium, the seven major stars align. A During the Alignment, the laws of nature get distorted, and magic grows stronger. Dead come to life, and nature's creatures get twisted and unnatural. But, as it was also discovered, the barrier between worlds gets weaker, and rifts begin to appear. Portals to a different dimension.
Millennia ago, some of our ancestors embarked on a voyage in the rifts to explore the new world; its lands, seas, and discover new life. Several years after, at the end of the Alignment, the rifts started closing. These first explorers got trapped, never to be seen again. Our ancestors called them the Forlorn. Lost to their kin, alone in a strange new world.
The following millennium, the rifts opened again. People from all cities gathered to the rifts, hoping to see the offspring of the lost ones return from the other side, ready to celebrate their homecoming. What followed will forever remain as one of the darkest days of our history. The descendants of those past explorers did come through the rifts, but they were different. They were filled with lust for blood, and massacred everybody who had gathered at the sites. Their magic was powerful, and tempered. They brought armies of hideous creatures, as bloodthirsty as they were. With great coordinated effort, all cities ceased their infighting and united against this common foe. They were able to push them back, until the rifts closed again.
Since then, every thousand years, the rifts open again and the Forlorn come through. Ever stronger and better prepared, they are trying to return to the lands of their ancestors, but only to defile them and stain them with the blood of innocents. We have also grown more vigilant, but the cost of this perpetual onslaught is high. Entire civilizations have disappeared. Sunken cities lie below the waves, others have been abandoned and succumbed to nature, others burnt to ashes. Scholars of ages past have noted that rifts have been growing in size and duration at every cycle. The Forlorn have been using this change to bring even greater horrors through the rifts.
Our astronomers warned us that the stars are almost aligned. Magic has been getting stronger again, and dead have been rising from their graves. We fear that rifts may open soon. But there is still hope. Rumors speak of an ancient scroll that contains the secret to a powerful ritual, invoking old magic that is able to seal the gates to this distant world forever. This knowledge, now in fragments, scattered and lost throughout the land, can finally turn the tide in this unending conflict."