Aether plague
From Dreams of Hope
A demonic weapon designed to neutralize Tal Elamor in the run-up to the Cataclysm War. A bunch of jotnar bound into insectile form, they consumed all the aether (especially active magic) in their vicinity, using that to replicate. Contained by the sacrifice of the last archdruid, Archibal trapping it in his own body in the middle of what became the Primal Forest.
Later cleansed by Ad Elementis, with the jotnar being reborn as Bianca Kelshanne.
