Backpack of Piggybacking

This backpack has a central pouch and two side pouches, each of which is an extradimensional space. Each side pouch can hold up to 50 pounds of material, not exceeding a volume of 5 cubic feet. The large central pouch can hold up to 25 cubic feet or 1500 pounds of living material. The backpack always weighs 5 pounds, regardless of its contents.

Placing an object in the backpack follows the normal rules for interacting with objects. Retrieving an item from the backpack requires you to use an action and a creature within 5 feet of the backpack may use an action to enter or exit it. When you reach into the backpack for a specific item, the item is always magically on top. All creatures within 5 feet of the backpack have the amorphous trait for the purposes of entering and exiting the backpack.

If the backpack is turned inside out, its contents spill forth, unharmed, and the backpack must be put right before it can be used again. If a nonliving item that is not being worn or carried is placed inside the central pouch of the backpack it is transferred to one of the side pouches, or spit back out if those are full. If a breathing creature is placed within the backpack, the creature can breathe normally as though it had air or water.

Placing the backpack inside an extradimensional space created by a bag of holding, portable hole, or similar item instantly destroys both items and opens a gate to the Astral Plane. The gate originates where the one item was placed inside the other. Any creature within 10 feet of the gate is sucked through it and deposited in a random location on the Astral Plane. The gate then closes. The gate is one-way only and can't be reopened.

Notes: Utility, Container