Its an easy encounter, you just have to equip skills that will defend you from All-Curse.
All Elemental Damage including that from rings, bombs and spells will heal the dragon.
Jansen is required to be in this fight. Take Seth and Kaim on front row and Jansen, Ming and Sarah on back. Use 3 Combo skill with Seth and Kaim, and double cast Forceus with all back row. If you're good enough you might kill him in 1 round.
When the battle is over you will get the strongest Black Magic spell in the game, Leveler.