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: ether, ether, 10 gil, 12 EXP

If Prize is 4 Materia:

Blue Chest: green, blue, black, yellow, 05 gil, 22 EXP

If Prize is 2 AB Letters:

Blue Chest: letter19, letter14, 10 gil, 32 EXP