Bolts
What fascinated Sylas the most about this technique was that it didn't work with a unique Aether. It used neutral Aether, and it was also an advanced application of Aether skin.
Sylas had to learn how to apply Aether skin himself by observing others and had never really had systematic training. But looking at the concepts in <Vortex Capture>, he realized that he had quite some room for improvement.
'I should also change the way I view Aether as well. It's not just a separate energy of the world; it is the world. It's the very energy that decides even how much particles vibrate in the air.
'When I expel Aether from a region, I form a vacuum because all the air in the region is Aether and Aether is the air…'
That made Sylas realize something else.
In that case, if space was a vacuum, then there was likely no Aether between planets.