Final Fantasy 12

This battle is a cakewalk almost regardless of how you slice it. How have so many potential advantages to aid you that you almost have to go out of your way to lose. Let's examine just a couple of those.

Here's an idea: have the character who spent a whopping 10 LP on him, summon the Esper Belias. Belias will quickly make short work of all the guards then go straight for Vossler. Vossler will spend half the battle trying in vain to weaken the powerful Esper as he is hit over and over again for 800 - 900 damage. You can basically sit there and twiddle your thumbs while Belias wins the battle for you.

If that doesn't suit you, then why not chain a few Quickenings. Sure enough it will wipe the floor with the guards immediately, and has the potential to eliminate Vossler in a single strike if you get lucky with the chaining. More than likely you'll have a few leftover hit points to pound out of him while he begs for mercy.

Those who, for whatever reason, choose neither option will be left with a battle that proves only marginally more difficult than a typical fight. More healing is obviously necessitated given Vossler's powerful strikes. The real danger comes once his HP drops to around 30% and he uses Enrage, which gives him the Shell, Haste and Reflect statuses. At this point Magick is totally out of the question, so just beat him down with the weapons you have available.

Keep in mind also (if you use her) that you won't have control of Fran for this battle, she'll still help, but she's not interested in following orders.