Yeah I also think challenges would be the best point to start, especially as it encourages players to try different decks.
Also have you thought about ways to enhance the grid later into the game?
On one side it feels limiting to just use a 3x3 grid, on the other side it could get difficult using card effects that want to be in the middle slot on a 4x4 grid. Workaround would be to declare a "center slot", maybe with a little windrose symbol or something like that and use that as center slot, even on a 4x4 grid where it wouldn't technically be in the center, if you know what I mean.
Challenges were added in the new patch, thanks for the suggestion!
Grid enhancement is something I’ve thought about quite a bit, but I’ve left it on the side for now while I focus on fixing and improving other parts of the game. It’s definitely noted though.
I can’t say for sure yet if I’ll add it, since it could drastically change how the game plays and how certain card effects are designed. As more cards and mechanics get added, I think it’ll become much easier to judge whether expanding the grid would actually improve the game.