Quote Originally Posted by Wolf Kanno View Post
You'll want Thundara attached to Zell and Squall's element junctions to maximize damage. Also draw as many Doubles from Elvoret as possible so you can have Selphie Dual cast Thunder/Thundara. Limit abuse is a must.

You get Thundara by learning Mid-Magic refine and converting Thunder spells into their tier two variants which should also be used to maximize Str. and Mag. stats. I would not recommend using Quezocaotl as the Boost option drags the fight out and the timer is your enemy for this challenge.
At level 20-29 you can draw Thundara from Caterchipillar.

Also, what about stocking up on Blitz cards then refining them into Dynamo Stones so they can be used to make Thundaga?