Ion

Ion is the living green energy that lives in the Green Lantern Central Power Battery

History
As soon as sentient beings developed willpower, Ion was born from the green wavelength of the so-called "emotional spectrum". Its existence has been kept a secret for eons, and it resided in the Central Battery on Oa to keep Parallax, the parasitic fear entity also imprisoned there, in check, as well as granting the Guardians of the Universe, Manhunters, the Green Lantern Corps a portion of its vast powers.

Regime Change
Hal Jordan, Kilowog and Queen Iolande are assisted by Ganthet, who imbues their willpower with the blue power of hope, giving them an enormous boost of power, that manifests in the same way as Ion when possessing a Green Lantern: a flaming green aura that surrounds the body of the Green Lanterns, temporarily increasing their abilities many times over.

Homecoming
Kilowog and Mogo receive an enormous boost of power by the assistance of Saint Walker, which once again manifests as a flaming green aura.

Scarred
It is revealed a fraction of Ion was utilized by Scar in the creation of Aya to make her more than just a regular AI.