UNLOCK: Capture at least one of every fiend in the Omega Ruins.
BOSS ANALYSIS : Vorban’s offense shouldn’t be much of a surprise to you; just look at him! He can use a basic physical attack, Body Splash (hits all), and Mortar. Mortar is used as a counterattack only for non-elemental magical damage to everyone; it seems to be used with every 1~4 attacks against the boss.
MAIN STRATEGY : Clearly enough, you need Protect and Shell (Auto-Protect/Auto-Shell) from the start. Mighty G, Super Mighty G, and Hyper Mighty G all work well enough for this bit of it, though all you really need is Mighty G then Hastega/Auto-Haste. From there on, just keep attacking with whatever you’ve got. Quick Hit is the main recommendation since it can give you can extra turn on the off-chance Mortar is fired so you can quickly throw up Curaga if needed. Nothing beyond this.