When we entered Emerald nightmare she was our first challenge to beat. Or rather that is not complete true as the trash before her was so annoying we actual wiped once or twice on it. When we finally engaged her we found out that she deals alot of dmg and could be hard to heal with 3 druids healers in our healer setup (have to take what we have and 3 druids are better than no healers). We also found out that with our dps at that time we could literal just kill her just before or during the berserk timer if all dps were alive untill the end.
After 2 raid evenings on her we finally managed to kill her and to progress further into the raid.