I think that the easiest (and economical >_>) way to complete this is finding a duo partner (or solo for the brave RDMs out there) and fighting Whiro, an eft NM in Abyssea - Atthowa Chasm. A rdm/nin should have no problem taking it down. A basic setup with a PLD tank can also work as long as the DD run away and kite it when it starts to spam Cyclotail. It is a very simple fight as it's not immune to gravity and can be kited quite easily. It is however, immune to bind. (or very resistant to it as I only cast it once and was resisted and didn't bother to cast it again) The hardest part of the fight is pulling it since it pops surrounded by normal efts that do link with it. Conflux #2 is nearby and you can attempt to zone the links.
Killed it yesterday as RDM/NIN(me) NIN/WAR(would voke and kite) and a BLM/NIN that showed up about 50% in. Spammed Thunder IIIs and Blizzard IIIs. Did not cast Aero IV since I didn't want it to build a resistance to wind. Thunder IIIs went unresisted every time for 560+. Kept Bio and Poison up the whole fight. It does have rapid hate decay making it even easier to kite and/or bounce hate. After 3 Thunder IIIs in a row the ninja was able to take hate with a voke. Dropped BLU and WHM head seals.
Happy hunting!