A massive iron key - 2’ length, 20 lbs forged with demonic faces from the bones and horns of demon-lords. When used with a massive portal - carefully built according to documents found in powerful books of evil knowledge, it will open into the realm of demons and allow them to flood into the world. The applications of this item for villains are obvious. Mortals touching this item are subject to [Effects_of_Touching_Powerful_Evil_Artifacts]
"Many strange things may be seen in the Great Swamps, not all real. But I tell you, there was a ship and it was real! Well it was old and all sails torn and had many holes in the hull... but anyway it was hundreds of miles from the Sea! How it came to be there, I can only wonder..."
(If it is not a hallucination, may be inhabited by wererats.)