Heroes Blade App
This is my current addiction, and I've never played a 'card-based RPG' before in my life. But do NOT listen to the iTunes reviewers - the game is winnable and the bosses are beatable. I'm already up to Level 5 and still going strong. You will replay each level, which consists of 3 normal 'battles' and a boss 'battle', but each time you win these battles you get money to spend on upgrades. Keep upgrading and then you'll finally be prepared to face the boss and win.