The Sage's Cave
Seems like he's living a nice life for himself here, all alone at the tip of the peninsula. He immediately clocks us as the ones who defeated the vampire, and lets us know that he was but a servant, and that the beast corrupting the Earth Crystal lurks much deeper within the cavern. Of course it does.
But he does give us a staff - the earth rod - that we can use behind the vampire's chamber, I assume on the stone slab that we found previously.
It's good that we can progress, but it feels like we basically need to backtrack all the way to the depths of the Cavern again. He doesn't even have anything to loot...
The journey there is uneventful, until the depths, where just before the slab Rukus and Kaili both get paralysed, so this is Glitz's time to shine as he busts out a Blizzara to take out a swarm of Ghasts and Wights.