Job Combos

[Urthdigger]

BLM add another Thunder that replaces Thundaga in the combo....
when used in a combo instead of Thundaga, this BLM thunder spell does greater damage the lower your HP is.
A few things immediately spring to mind. BLM has an ability that switches MP and HP
So you use up all your MP... switch values of your MP and HP and then do this combo.
Your HP will be extremely low and the new BLM thunder spell should do serious damage

For bonus points, toss in necrogenesis before the final spell to top your HP off so you can blow through your MP and repeat.