Thank you, yes I agree that the late game needs more balance. Applying the multiplier to buff effects is a good idea and I think it will help a lot. I'd like ta also add artifacts that can have passive effects or effects at the start of a new combat, which should help the player survive better. I will also be adding more features to the map, like rooms where you can heal back up to full.
Having more matches is an interesting idea, it would make things slightly more difficult in theory but since it would allow additional cards to be played you're right it would increase your chances of survival if played well.