In the CCG Hearthstone add-ons called Deck Trackers exist that track what cards are left in your deck with some even tracking what cards you draw as well as what cards your opponent has used as well. Now obviously doing that for Wizard101 where up to 8 fighters (4 opponents in this case) can be in any given battle at once can be tricky, so maybe just limiting it to tracking what cards are left in your deck (and maybe what cards you've discarded as well) would be fair and simple enough.
Now some might be thinking that this would give an unfair advantage in PvP, and in some respects you may be right. However, Hearthstone is primarily a PvP 1v1 focused game and other than showing what cards are left in your deck it provides no real tactical advantage over the opponent.
in my honest opinion i think it's just kind of pointless to integrate this into the game. a deck is entirely reliant on the holder to know what cards are in their deck, what they've already used, and what they've got left.
Sorry but that is just my honest opinion. But I can see how it could be beneficial to those with bad memory, however considering the size of the spell decks it really poses no benefit for just about everyone else. Now if the spell decks were able to reach say well over 100 maybe 130 then yeah this idea would definitely be a must have idea. But as for now it’s just unneeded data and unnecessary coding. If it were added I’d suggest an option to turn it off in the settings at least.