Great Gaelach's Moon

Once a year, during the colder months, when food must be stockpiled and the trees shed their coats, the world of Umbra experiences a dark phenomenon known by many different names across the world, in which the normally large, luminous celestial moon, turns against the population of the world, bestowing a single night of horror and abysmal misfortune.

Some know it as Great Gaelach's Moon, and it can be summarized as one particular night when everything that could possibly go wrong, certainly will, and in countless locations around the world, disaster and terror will manifest unchecked. Beasts siege villages, dragging kicking and screaming innocents into the treeline, vampires both strike down their cattle in droves, and are themselves burned alive by zealous mobs, all driven into a frenzy of fear and electric anticipation for this night. By the time the sun rises on Umbra, the clouds will be stained rich red from the blood spilled before the morn.

An individual finding themselves bathed in this moonlight would feel an unsettling and chittering sensation, inciting normally unthinkable acts. Looking up, they may see dark tendrils snaking across the lunar surface, or maybe hear it's pent up maniacal laughter unleashed for thew few hours. Some swear that they have seen the moon split and reform like a Spirograph in the sky, though its true that the wise spend this period huddled around a fire with their loved ones, weapons unsheathed and in hand.