Bag of Transmutation (5e Equipment)
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Wondrous Item, legendary (Attunement by placing an item that you are attuned to into the bag, sacrificing the item. (not transferring it into energy))
A Bag of Holding V that has been repurposed by a legendary wizard to consume the essence of his items in exchange for other items of more or the same item.
Transmutation: You place an item into this bag and it vanishes into an unseen plane of existence where it is transformed into energy to be withdrawn later. The amount of energy is determined by its rarity or worth or by the DM. After the amount of energy has increased you can either withdraw the same item as if it were a Bag of Holding V or you can summon an item that you know a great deal abount (your shoes for example) from the bag, exchanging the energy of a deposited item (or the same item) for a new item. Legendary items can be withdrawn from the bag if a legendary item of equal or greater value has been deposited and you know the absolute exact details of the item. The item must also be able to fit out of the bag (which is the same size of a Bag of Holding V) This bag can reproduce currency as long as you know it fully and have items energy of equal value to exchange.
The DM also decides whether or not you know an item well enough to reproduce it, (eg. if you wish to reproduce a key to a door, you must know exactly what the key looks like, what it's dimensions are etc.)
If you try and reproduce an item but do not know it well enough, you pull out an item that is similar to what you were looking for but is not.