How do I level up? I have to say that I am on easy mode I think, but those battles when I have 130 hp and others have 1,7k are quite hard.
Theres an item you can buy from a person in the arena to increase your max hp by 5 at the end of the day and the succubus deck that can sometimes increase your max hp permanently other then that the restaurant with the one food option that can give you a random hp increase for one battle also for the succubus deck it also have a few hp steal cards or healing and it's boss card "Belial the first who's attack increases by 5 when you play a certain card its attack stays increased until you lose the game or getting on one the endings by the time I got my first ending well the bad ending its attack was over 1k