OK so me and a few of my buddies were running kings fall. Once we defeated oryx and went up to the chest and got my items I checked my inventory. Surprisingly the raisins instead of saying discard it said use. When I used the raisins at the chest I was awarded something secret. We tried with another person that had the oryx checkpoint but it didn't work. My guess is that for you to get the secret loot you have to play the raid fresh. It is totaly worth it guys, go check it out.