Ethereal Darkness
Those with knowledge of Nethermancy are unaffected by Ethereal Darkness—they can see normally, as if the spell had never been cast.
What defines "Knowledge of Nethermancy"? The Spectral Dancer Horror Construct, or a Spirit with Nethermancy spells aren't Nethermancers, but logic dictates that they have knowledge of it since they're using Nethermancy spells? Theoretically, albeit silly I know, having a Knowledge skill called Nethermancy would render you immune to the spell, which I gather is not the intent
