This ancient bag was originally created to hold a black hole that threatened life on the entire material plane. The wizard who created it nobly volunteered to seal away the imminent threat. In the struggle to capture the black hole, the wizard vanished, along with any threat to the planes of existence.
This bag has a large plane of existence inside of it, tied to the creature attuned to it. Any creature who has attuned to this bag has their own demi-plane inside the bag, with endless space inside. The bag will adjust to whatever object is being placed inside/taken out, larger objects take longer to, but normal sized objects (Dm's discretion) can be placed/taken out of the bag using an action.
Creatures in the bag suffer no adverse affects, such as suffocating like in a bag of holding, but time inside of the bag is warped. A creature who enters the bag while living will roll to see how the time in the bag has passed compared to the material plane once they exit.
If the bag passes to a different creature, everything placed into the bag by the previous owner remains, and the new owner cannot access the items of the previous owner. If an owner decides to access items from a previous owner, they may make an Arcana check with a DC set by the DM.
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