Really cool game! I almost got a flawless first run, but the final boss of round 3 took me two tries.
If this game is ever expanded on, perhaps some more options in the shop could be a great addition. Different packs for example, where packs with higher costs increase the odds of getting a certain character. Once I got the party I wanted around midway during the game, I did not feel the need to visit the shop anymore.
Overall a very enjoyable experience, well done!