Board Thread:General Discussion/@comment-74.10.105.99-20130523200150/@comment-81.62.141.122-20130602173545

If you don't use the power attack on the boss you will only get the normal shards as a loot.

But as the first commenter said it depends on the difficulty of the stage. Now you have to decide if you want to be able to make more runs (normal stage) or if you want a higher chance of getting the right loot (epi stage).