The card system sorta reminds me of Kingdom Hearts Chain of Memories. It is a pretty smooth experience, and while it has the usual rogue stuff. You can permanently upgrade, and tackle the game at your own pace.
Funny enough, the first boss fight. After losing quite a bit on the way. The boss fight I end up going into it with basically no cards and power ups and won.
You can permanently upgrade, and tackle the game at your own pace.