Mission fights in Issue #5 (1-2 per fight won on Normal difficulty, 2-3 per fight won on Crisis difficulty)
Note: Before the May 9, 2013 patch, these were randomly dropped in six different colors, rather than being guaranteed per fight won. These were automatically converted when the patch came out at the rate of 1 old item (of any color) to 10 new items. See here for full details.