The tough ones are comming!
3 new boss zone stages are added. Unlikely other stages, immediately after entering the stage, you will face with Boss Monters.
With various quests, you will be able to earn valuable game item including Myth Stage Boss Box, rebirth item, and even avatar items. But then, you will be able to get limited number of keys which you need for entering these stages. Hope that you use given keys wisely!
Here are 3 stages!