Beware the Bagman

Van Richten told us an urban legend in his guide to Ravenloft, about an adventurer, who sought to escape doom by abandoning his party and hiding inside a bag of holding. But when he tried to leave, he became lost amid a constantly increasing number of extradimensional storage spaces. Over time, the strange forces of this magical in-between place transformed the adventurer into a monstrous creature. Now, every night, the Bagman slips out from a random bag of holding. If he doesn't find his home, he drags someone back into the bag with him and leaves behind some trinket from his hidden kingdom of lost junk. Some say that if you speak too loudly over an open bag of holding or whisper "follow my voice" into a magical storage space three times, the Bagman will come for you.