Board Thread:General Discussion/@comment-26063681-20150201030104/@comment-18293-20150202042400

I believe Mu is balanced. It provides a challenge for those strong enough (ie. those who finished clearing the map, or are close to it), and have good rewards along with it (spirit drops).

It is not meant to be easily farmed unlike the rest of the areas. I mean, you can clear most other areas with minimal damage, and Mu definitively is a welcome change of pace.