So, now we have the trailer and a bit of dialogue, I suppose it will go something like this;

Darklander and co have their own crystals to capture the aether released when a primal dies. Instead of it going back to Hydaelyn, they're intercepting it for Zodiark. Hence the Ravana fight in 2.1. Hence Ifrit, Titan, and Garuda (briefly) showing up in Xelphatol.

Or... they're using it to power up the Heart of Sabik