Refresh for each blue chest and take appropriate reward:

If Enemy shows up, he takes away:

If Rival shows up, he takes away:

If Both show up, use Rival!

If Prize is 2 items:

Blue Chest: phoenix, remedy, 05 gil, 11 EXP

If Prize is 4 Materia:

Blue Chest: purple, blue, yellow, green, 10 gil, 35 EXP

If Prize is 2 AB Letters:

Blue Chest: letter15, letter18, 05 gil, 27 EXP