Here we would post some useful job/ability combos, if you have any to share, feel free to e-mail that to us.

Combo involving only one member:

Blue Mage x Devout or Illusionist x Devout (by sarcasteak)

First of all, the new MP system of FFTA2 greatly impacts ALL spell casters, not just the Blue Mage. Basically, everyone starts out with 0 MP at the start of the battle and gain 10 MP every turn (or 20 MP with MP Boost Clan Ability), and MP costs of spells have been reduced and adjusted accordingly. Of course, there are many ways to completely negate or somewhat bypass this MP limitation, so it's not something you can't get around. Now, I haven't obtained the spell yet myself, but this new MP system theoretically would make Mantra Magic uber godly... enemies will have 10~30 MP at best by the time your Blue Mage gets close enough...

Instead of using it to induce full-screen Sleep, Night can become a full-screen attack spell when combined with Devout's Magic Burst. Of course, full-screen Sleep is probably the more desirable effect (and that you should probably leave this whole Magic Burst business to an Illusionist), but hey, it's always nice to have another option. Anyways, for optimal effect, you can dual-wield your Blue Mage two elemental weapons (I use Fire) and then gear the rest of your units with equipments that absorb that particular element. With Magic Burst, your Blue Mage will cast Night on every unit on the map and then follow it up with a double attack on every unit you just targeted--you give up the Sleep effect for full-screen damage and full-screen healing. Fun, though probably a bit impractical.

Combo involving more than one member:

Scholar combo (by Penguin Knight)

This combo exploits the hit-all effect of scholar's knowledge technique. We are going to create two scholars with MP Absorb technique. Because it's hit-all, so the other scholar will gain and retain the MP, pretty much making both of them a spell factory. In the same time, we also exploit the fact that (so far what I found) there are two clothes can be worn by all jobs that absorb element. In that case, you recover every member, and hurt every enemy.

What you need:

1. Two scholars, who can either use the Dark (漆黒と冥闇の書) or Earth (大地と竜脈の書) spell. It'd be much more efficient if both of them have learned MP Turbo (MPターボ, from White Robe, 白のローブ) as support and MP Absorb (使用MP吸収, from Robe of Lord, ローブオブロード). MP Turbo allows you to double your MP requirement of spell and also its potency, MP Absorb allows you to absorb equal amount of MP of an invasive spell casted on the character.
2. Six Bone Plate (ボーンプレート, if use Dark spell) or six Earth Clothes (大地の衣, if use Earth spell), one for each player.
3. To kick off the spell battle earlier, dump in a Magic Gunner who can use Ether Cannon, it recovers 40 MP after one charge. That way, it allows the effect of MP Turbo to shine.

Because you never "lost" the MP between the two scholars, it's actually pretty powerful. Also, you can change them to Alchemist, who has higher Magic Attack gain. Notice that you have to set up the party like this:

- If both scholars has Robe of Lord, and can cast Dark Knowledge, then give them armor OTHER THAN Bone Plate

- Give a Bone Plate to the rest of the members

Because MP Absorb does not work if the character didn't get hurt, if I remember correctly. For a high-level scholar, usually two shots of knowledges can wipe out things like dragon if it has an elemental weakness.

Powerful Combo (AoE + MP Refresher Combo):

Cannoneer & Illusionist combo (by Moonblade)

Firstly this combo is powerful; So long as you dont want to take laws into account when battling this is a full on barrage of death by AoE magic and could probably clear the map in one turn.  The simple setup I would recommend having the following abilities set:

Illusionist:

Reaction: Replenish MP (Hume Only: When taking damage you will absorb a portion of that damage to MP *Requires Seer + Black Robe)

Passive: Turbo MP (Spells cost twice the usual to increase the potency *Requires White Mage + White Robe)

*Optional Hume (If you go Illusionist/Seer (subjob) you can have re-charge increasing the mana amount greatly but this is not really needed)

*Optional Nu Moo (There is more Magic damage potential with this race, however, its your choice what you prefer.  There are many good combos to work with here my favourite is the Illusionist/Scholar combo so long as you set your absorb abilities right with your group of spell you want to AoE with; on another note for a faster pace you can go for the /Time Mage sub job (play around see what you like)

Item of choice: x2 Golden Amulets for Extra Magic Damage!!

Cannoneer:

All you need is a Brevis (Cannon) which provides Ether Shell ability (*Note: Flintlocks get this but they have to prime and only output 40 MP every 2 turns (including the prime turn) while Cannoneers Output 60 MP a turn! Where an Illusion spell costs only 58 MP!!!)

This is the basic setup; just by looking at this if you haven't tried it yet you will know that all you need is a healer in there, possibly any other tanks of dps out in the front (Love my Master Monks) and you are set!  The speed difference in classes usually allows the Cannoneer to go first and do the Ethershell on the Illusionist and from there when its their turn they can blast away!  Its your choice between Hume or Nu Moo; I have been using Hume more often but Nu Moo can be a lot more beneficial.  You can play around with the setup if you prefer using a Scholar instead of an Illusionist, however, this is entirely up to you.  Illusionist have a wider range of Elements to play with compared to Scholars so this is the main reason I would prefer an Illusionist over a Scholar.  But the Cannoneer has made MP reliant classes very easy mode with a 60 MP restore Ether Shell you can even pass this onto Hunters for more Ultima Shot doom.  Have Fun!! :)