While fighting along-side Greham, the Jade Dragon uses to two attacks and one Power Up skill. Its two physical attacks are the following: Feeler Whip, in which the Dragon uses its feelers to attack one ally, and Buttocks Attack, which has 50% chance of inflicting poison, stun, or fear on one of your allies. Feyrbrand also has the ability to do a Power Up, after he is hit by a magic-based attack, which gives him 10% chance of doing extra damage.
Feyrbrand is tricky in that he tends to cause poison, stun, or fear on your allies. He is the best one in this battle to attack first because of this. With some strong Additions and perhaps a magic attack or two, he should fall easily.