It is a large chest made of sentient wood (a magical, intelligent plant which became extinct in the 4th Age.) It can produce hundreds of little legs protruding from its underside and can move very fast if the need arises. It has been described as "half suitcase, half homicidal maniac" to any who are lucky enough to get in it's way and survive to tell the tale.
Chakra: Wonderous Item
Property: This large, wooden chest follows it's owner wherever that owner goes. Through hellholes, the overworld, everywhere it's owner goes, it follows. It also has unlimited, airless storage inside of it's gaping maw. The Luggage is sentient, and has a mind of it's own, so the GM should treat it as an NPC based on the property above.
Attunement: You don't attune to the Luggage, so much as you survive it. You must defeat it in combat and strike the final blow, before it will follow you. Or it must be given to you, freely, by it's previous owner.
See: The Luggage (monster)