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, terra, 20 gil, 38 EXP

If Prize is 4 Materia:

Blue Chest: red, green, blue, black, 05 gil, 30 EXP

If Prize is 2 AB Letters:

Blue Chest: letter14, letter01, 05 gil, 23 EXP