You get this assignment from War-Chief Supinelu from Jahra. He can be found in the south part of the village. He needs your help to kill an eternal enemy prowling in Zertinan Caverns.
Go to the cave. To get to Catoblepas's Lair you'll have to pass through a hidden area. After you enter the correct area you'll be greeted by Supinelu.
About 166 000 HP
Resistant to Libra,
Vulnerable to Holy
Smite of Rage,
Protect, Shell, Haste
During this fight the Supinelu himself will come to your aid, but, I hate to say it, Supinelu isn't as good as he's told to be.
At first the enemy uses only normal attack (which harms him also), Ram and Tail Swipe, which deals damage to everyone standing around him.
With time, when he loses about 50% of his HP, he starts using Smite of Rage and the buffs. At the whole beginning Dispel him and later on do this as soon as he casts a buff on himself. Get rid of him quickly and run to collect your bounty.
Bounty: 3200 gil, Volcano, Arctic Wind (1179g)