so i've played some more of the game, and the big thing i've noticed is that cards which interact with lanes are far worse when there's only 1 lane, and i think that's problematic. what if there were 4 or 5 lanes, but you still won upon getting 2? i don't know if that solution necessarily works, but i think this could be a pretty big problem that you need to analyze and figure out how to approach it (if at all), and i think it's important to stress this.
that said, i'm still really enjoying the game, i think you're definitely on a good track! unrelated side note, it seems like the sellsword is quite good, possibly too good, especially on the last lane where the money loss doesn't matter. problem is that there isn't much of a way to nerf him, just due to the way he works, so he ends up in a weird spot as a result.
also, it feels like there are a lot of strength-based cards without utility (e.g. paladin, berserker, fairy, necromancer, etc.), possibly too many, so maybe fairy could be cut? her ability is generally so neutral if your opponent is contesting the lane at all, she may as well not have it, as it'll generally only be a 1 or 2 point difference, sometimes not even in your favor. (and if your opponent isn't contesting the lane, then why do you want a strength card?)
also, a card suggestion: "score: destroy any number of your cards in other lanes and gain strength equal to the total strength of cards destroyed this way." might be too long to fit, but i figured there was no harm in putting it here. and i should say again that i really do like your game, it's really good as-is, but i also have some concerns and suggestions that i think are worth bringing up.