Heart of Fear, Grand Empress Shek'zeer problem

I’m in Heart of Fear Raid, PANDARIA
Heroic, 25 man, solo

When I get to the Empress Shek’zeer I get her to about 1/3 health. She then used Cry of Terror and I get transformed into some black and white monster and the whole thing resets.
I’ve seen mention online of her dropping something on the ground affected people can stand in? I don’t see anything on the ground. Help