This is very interesting.... I'm just a hobbiest game dev so I haven't tried making any game that uses online functionalities (big ones, because small ones like interacting with a simple API is easy)...
I hope you can make this!!
by the way, you know about the game that uses crypto Spells of Genesis... it has (probably all) the mechanics you want to do, but it's a card game... not a 3rd person that uses cards.