Selling your cards is legal. Forking some smart-contract blockchain project to make a card ownership/trade tracking system for your group of friends is also legal. Advertising using WotC’s trademarks or selling the virtual tokens you create that way would not be legal. You can use NFT’s for the accounting, but it needs to be clear that they have no value and are only following the physical card as it changes ownership. That part also means you can’t use any existing defi or public blockchains and would have to roll your own.
It’s an overkill use case, certainly, but it could be used to track card ownership/trading, and as a way to control power creep with arbitrary scarcity. You could also do the same thing with a spreadsheet, but if you want an excuse to play with smart contracts it could be a fun project to implement. Blockchain/NFT tech is just code, it doesn’t have to be energy-intensive or grifty. It just invariably gets there when money is involved.
