Make the NPCs follow Deck Limitations
OR
Let us pick more than 1 high level card.
Because HOLY HELL Isobe is the cheatiest NPC I've ever seen. Entire deck is 5-6 stars with 1 2 star JUST so it might switch and ruin your deck.
It's not Hard. And screw "But then it'd be easy to farm them" Well GOOD, because the chance drops of these cards is PATHETIC. PURELY to make you waste time and keep that sub going. Theres no reward from playing this except for more cards.