The petitioner on this one is Va'Kansa, which can be found standing near the seller in Mosphoran Highwaste. He had been attacked by a giant shining horse and his companion has disappeared. He asks you to get rid of that creature.
About 45 000 HP
Resistant to Libra,
Resistant to Dark, Water, Fire,
Vulnerable to Ice
You'll find him in the north-western part of Salikawood, just before the entrance to Necrohol of Nabudis. To get there first you have to kill an additional boss: The Bomb King (see the section: "Bosses not connected with the Plot").
His attacks are: Snake Lash, which damages your every character, invert, which changes the amount of MP with the amount of HP, Berserk, Thundara and Bleed, which may cause Sap.
First send a berserked damage dealer to fight him, and forget about any weapon with the element he's resistant to, because it will cause exactly... 0 damage. Leave one hero at a distance with long ranged weapon and a healer.
Bounty: 1700 gil, Obelisk, Hi-Ether.