The Performer is a singing superstar who can aid its allies with the power of song. Its stats generally range from mediocre to average, but it has decent Agility, making it one of the faster support-based jobs. Rather than fighting, it functions best as a healer and support hybrid.
Performers are a boon to the party with their attack, defence and BP-boosting songs. Meanwhile, Power Up ensures your Performer becomes nigh untouchable during long battles, so long as the enemy can't cancel your buffs. Sadly they can no longer boost speed, but it's not a necessity here.
Specialty: Power Up
At the end of each turn, the user's Physical Attack, Magical Attack, Physical Defence and Magical Defence each increase by 5% for five turns (up to 150%).
This ability is amazing, for prolonged battles at least. After 10 turns, your Performer will have insane buffs, even allowing them to shrug off attacks from lesser bosses. 10 turns is a long time to wait, but you can use the Performer's buffing songs to get there quicker.
By the way, the five turn limit is a bit of misnomer, as Power Up will continue to trigger even after reaching the maximum value, which means the buffs actually last forever. Or at least until your Performer gets KO'd or the enemy dispels your buffs.
Level 1: Love Power
Slightly weaker than the Astrologian's Physical Boon, but it affects the entire party without relying on Spellcraft of Group-Cast All. Also weaker than the Catmancer's Panzerlied, but not by much. A nice middle of the road buffing ability.
Level 2; One More for You
This essentially transfers one of the Performer's BP to another character. It's not as game-breaking as some BP gaining exploits, but it's quick and easy to use and has many applications. For example, to give an attacker some extra juice or to bring a character out of the red.
Level 3: Got Your Back
In a similar manner to Love Power, this is slightly weaker than the Astrologian's Physical Ward, but you don't have to waste an extra 1 BP to use Spellcraft or 2 ability slots to equip Group-Cast All. An easy way to bolster your party's defences in a jiffy.
Level 4: Encore
Not the most reliable of abilities, but fairly useful early on when your Performer is learning the ropes and there are no better support-based abilities to equip.
Level 5: Key to Your Heart
The magic version of Got Your Back. Handy to have when facing enemies with powerful magic-based attacks (and where Elemental Barrier is insufficient).
Level 6: Little Devil
The magic version of Love Power. Great if you're relying on spell-casters for attacking. Although if you're running ghost mages, be aware that you can't buff them.
Level 7: Power Up
The cost is noticeable, but it's a fine all-purpose ability for any job. So long as you're content being the tortoise rather than the hare. In particular, tanks will probably appreciate it the most.
Level 8: Zero Sum
A good counter against foes who like to build up BP. Can also render them immobile if they're silly enough to Brave multiple times during the turn you use this.
Level 9: My Hero
For its cost, this essentially transfers 3 of your Performer's BP to the other 3 party members. Useful if your Performer has excess BP and nothing else to do. Can be abused with Mimic to give your party more BP than they ever need.
Level 10: Hearts on Fire
An exceptional ability that combines the best of Love Power and Little Devil, for the ultimate offensive party buff. No complaints at all!
Level 11: The Grand Ship
A nifty ability that combines the best of Got Your Back and Key to Your Heart, for the ultimate defensive party buff. It might seem a tad unexciting for a final ability, but you can't fault its usefulness, especially when up against threatening foes.