In Porto Liure, there's a very unusual cult: the worship of Dog. Dog is a "god" that's actually fairly apparent to the residents of Porto Liure. Everyone knows about him. He lives on the island of Gandesa, not far from the city. He appears to be immortal--he's been there since the city was founded at the very least--and undefeatable. In the early days of Porto Liure, soldiers and sailors tried to hunt or kill Dog, but most were killed and eaten for their efforts.
Mostly Dog sleeps on the island, unseen and hidden from view. Nobody knows where his lair is, despite many efforts to find it over the years. When Dog walks, he leaves dark footprints behind that ooze shadowy tendrils of darkness like oily black smoke, but if one tries to track Dog, the tracks always seem to end in a confusing maze, or circle back on themselves, or otherwise lead one to naught.
Nobody is exactly sure when worship of Dog started. It became apparent that Dog needed to eat. Three times a year, human sacrifices are left for Dog. Usually they are convicted criminals or enemies of the state, but if none are available, occasionally a citizen will be sacrificed. Dog prefers young maidens, but will take anyone that's not too old and stringy. If Dog isn't satiated through sacrifice, he will slip into Porto Liure at night and eat anyone he can find in the streets, leaving nothing but bloody tatters in his wake. In the summer of 421--almost 150 years ago now--Dog massacred no less than 43 men, women and children in a single night and was seen by many more, before slipping off again before sunrise, leading to the last attempt to hunt and kill him. Unsuccessfully, of course--he wasn't even found after the Bloody Saturday Massacre, as it came to be called.
Another curious Liurism is that portegnos frequently swear by Dog, even if they don't belong to the admittedly small cult of Dog. "By Dog!". "By Dog's rancid breath!" or "By the fleas of Dog's greasy pelt!" and countless other variations pepper the speech of most native portegnos.