Eidol Gas

"Eidol Gas", also just referred to as Asaeic Gas, is a unique manifestation of Asa, pulled from the asaeic plane into the physical realm. In its essential form, Eidol Gas is a shimmering, ethereal substance, visually reminiscent of a faintly glowing light blue, purple, and magenta vapor. It possesses immense potential energy, making it highly sought after for various magical applications. It can be used to directly fuel asaeic abilities for those skilled in using it, but it can also be used in a variety of technology such as Spellbinding Devices.

Source

The gas is harvested from maelstroms in the Mists of Passing, which not only leak raw asa in the asaeic plane, but can also manifest it in physical forms. This is very dangerous, given the nature of the depths of the mists of passing and especially the maelstroms, but the sheer versatility and power of Eidol Gas makes it well worth.