Aether Core Creation
The method of creating an Aether Core wasn't that complicated if the mind was powerful enough, but there were certain precautions to take if one wanted to create an Aether Core inside one's body.
The Aether Core was originally just a mass of Aether belonging to no one. If its creator wasn't careful, he or she could spend days or even weeks at a time accumulating Aether, only to find that at the first move, the Aether Core had stayed behind in the very same spot.
Though, most often by disintegrating all the flesh and organs that had been in contact with it... So the first thing to do before creating an Aether Core was to make sure that it was firmly anchored to the body of its creator and not spatially locked in the space where the Core was generated.