The Sever activities are the seasonal story missions of Season of the Haunted. They are located near the bottom left hand corner of the map of the Moon.
Overview
In order to sever the connection of Emperor Calus and The Lunar Pyramid, Eris Morn had invited The Guardian, Crow, and Commander Zavala to take place in a ritual that would expose their deepest fears and regrets in the form of Nightmares. The Sever missions follow Crow, Zavala, and Empress Caiatl as the Guardian helps them combat their Nightmares and weaken Calus's grasp over the Pyramid.
There are six Sever missions in total, two missions per character.