After engaging her, all my ability cast times increased like hundredfold. Disturbance cast time was over a minute. Telekinetic throw channel time was over 100 seconds long.

During the fight, warzone popped up. I accepted. After the WZ ended, i was put back into the story instance. Engaged lachris again, and the same thing happened again. Finally defeated her thanks to instant spells and telekinetic throw (since it deals damage during the channel even if its 100s long)