Wondrous Item, artifact (requires attunement by a The first person that acquires the bag and has it during a long rest becomes the True Master. )
A strange bag of unknown origin. To most, it acts like a normal Bag of Holding. To the True Master, though it leads to a different realm. Features a small cabin next to an idyllic lake and surrounded by dense forest with mountains in the background. The cabin can sleep up to six people and is well furnished with storage chests, a larder and a magical butler named Waddle. The True Master can let people into the bag and can even force someone in if they fail a DC 12 Dex save. They can also remove people from the bag at will.
Notes: The first person that acquires the bag and has it during a long rest becomes the True Master.