Great game. It gets overwhelming pretty quickly when you have collected a lot of buffs/debuffs. The looks and and sound design are good, very snappy. I think armor and card draw are the best effects. You seem to pretty much need card draw to beat the later stages. And being able to tank 2 hits after a single move then keep the armor until next round is overpowered. Overall the buffs/debuff design was executed well. All the effects are useful and none of the penalties are too punishing.
Some more complex effects might be possible like "attack to the right after using a rook", but that would make your moves even more difficult to plan. One UI change that would help a lot is displaying the effects that are relevant to each card on the card itself with a little badge.