This addon adjusts the alpha channel of raid frames during The Desolate Host raid encounter in the Tomb of Sargeras. It does this by hooking the unit spell range checking functions and adding an extra check that the unit is in the same "realm" as you, whether it be the corporeal realm or spirit realm. Should the unit not be phased in with you, the unit status will be adjusted to look the same as if the unit was out of range. What the raid frames actually do will be based on your addon settings. Grid and Vuhdo do not fade by default but do have a default indication for out of range.
You would be a user if this addon if you are a healer that uses click-bind or mouseover style casting. Healers, like me, have an innate reaction to heal players that get dangerously low and the reaction is suppressed if the unit is indicated as out of range (>40 yards).
The addon affects your frames ONLY during the "The Desolate Host" encounter and will restore all previous functionality when the encounter ends.
I made this primarily for ElvUI but it supports Blizzard raid frames, Grid, and Vuhdo as well.
Be sure your out of range indicator for Grid and Vuhdo is on.