I think it would be an interesting implementation of multiple inventories. indeed, a "deck" of cards can be represented as an inventory, and therefore you could have inventories that represent
- your hand
- the main deck
- the side deck
- the extra deck
- the graveyard
If we consider each card to be an item, then various card/deck operations such as
- drawing
- discarding
- peeking at the top N cards
- shuffling
Can all be treated as various inventory operations.
Having a physical "inventory" item that is used to determine what your current deck is would also be an excellent way to handle things.
If you could event the battle logic to move cards from one inventory to another, then you'd have a lot of control over the rules of your card game.