History of Sever

Sever is a set of six story missions in Season of the Haunted, played on the Derelict Leviathan, near the bottom left of the Moon map. The goal is to sever Calus's link to the Lunar Pyramid; each mission has you face a "Nightmare" of a character's fear. They are grouped in three pairs, the first attempt failing and the second succeeding:

1. Shame / Reconciliation: Crow confronts his past as Uldren Sov. These are Sever - Shame and its follow-up.
2. Grief / Forgiveness: Commander Zavala faces guilt over his son's death (Sever - Grief).
3. Rage / Resolve: Empress Caiatl fights her nightmare of Dominus Ghaul (Sever - Rage, Sever - Resolve).

You move through the Leviathan's interior, solve puzzles (shooting fuses, carrying wrenches), clear enemy waves and plant Ritual Amplifiers. Missions drop Season of the Haunted weapons and armor and Opulent Umbral Energy, with extra loot for players with a Bound Presence (Destinypedia).