Nice idea, but it needs a bit less randomness. The first match took almost half an hour, where the enemy was on 5 hp or lower several times, but i couldn't attack because I had no cards.
Slavic castles is game strongly inspired by the Arcomage game from Might & Magic series. In future I would like to make it more unique but for now I focus mostly on mechanics.
Project is in development
You can also play it here: http://leinnan.ayz.pl/ukw/slavic_castles/index.html