Short version: Alastair regained control of Niccolo briefly. Death began to experiment on herself with sigils, and the others repeatedly begged and eventually forced her to stop because she was hurting herself. Niccolo and Zafira sparred together for a short while. Javier attacked Adra, then Niccolo (which triggered Alastair taking control again for a brief period of time), and then Zafira before they detained him and brought him to the Sanctuary.
Long version: I'm too tired for this.