Dante will definitely get Devil Trigger before Auron gets his overdrive. There are 10 symbols in Devil Gauge, Dante only needs 3 symbols to trigger it. And it takes about 3 grenade shots to charge it, or just by shooting Ebony and Ivory at Auron for about 8 seconds. It doesn't even need to actually damage Auron for the gauge to charge up.

As for Tornado, I said Holy Water. If Auron finally uses his Overdrive, Dante just needs to simply toss in a Holy Water to break the move and at the same time damages Auron.

Dante can fly, Air Raid.