Bardic Knowledge or Knowledge: Ancient History (DC 30)
According to the ancient lore, the trickster wererat Locri the Swift slipped into the werewolves' lair and replaced the humanoid blood in the cauldron with blood taken from animals. The Wolf King and his guards bathed within it before a major battle, only to die in a hail of silvered arrows as they confidently marched before a massed regiment of enemies. If the portents and fables offered by bards are correct, the werewolves swore vengeance against the wererats, promising to destroy the comfortable, secure lairs that the wererats had so carefully nurtured within cities for centuries. However, the lore ends that the cauldron's location had remained a mystery, thought lost to history, until now.