I was doing Il'gynoth tonight and noticed that the Mistweaver artifact talent Dancing mists was actually allowing renewing mist to spread multiple times (on the same 10% chance per spread).
At first I thought I was seeing things then one time it managed to spread to five people instead of one at the same time.
https://www.warcraftlogs.com/reports...9&end=10604031
As you can see at about 57 seconds in five people received the buff at the same time without it fading on anyone else.
I had cast it on one of the mages and it spread to 2 other mages a paladin and the priest.
Perhaps it always had a chance to spread extra times past the first (I've never read anything about it), or something changed.
in any case that was pretty lucky if you assume it happens about 1/10000 times.