Magic wish stone.
Often thought of as a double-edged sword in almost all conversations Oneirum becomes a part of. On one hand, presence of Oneirum and contained forms enable the use of magic, bypassing petty things such as thermodynamics and physics. On the other hand, Oneirum in the air, completely unconstrained, like the Oneirum carried by The Storm, causes typical illness symptoms of weakness, which can become problems in dives, but with prolonged exposure causes physical mutations and abberancy.
Storm Disease
Though the name was given after observing prolonged exposure to The Storm, the disease simply originates from unprotected exposure to high Oneirum concentrations.
Storm Disease manifests in many ways, but it often causes irreversible changes to biology and physiology without extensive, expensive, and high-risk surgery.