I've got some good news for you. I managed to set up the option to train against the AI today. Right now, the AI is only using one deck, but hey, it's a great way to practice and get a feel for the game.
It works like this: when a player registers, they start with a rank of 1000, and if they lose in PvP, their rank decreases. That’s why on the leaderboard, you see a lot of players in top positions who haven't played any games. 😄