Following the defeat of Maliwan's invasion force at Promethea, Lorelei believes they might regroup and try to attack Atlas again. She contacts the Vault Hunter, asking them to take the fight to Maliwan by raiding Midnight's Cairn and destroying their prototype war machines. After the Vault Hunter fights their way through the blacksite's formidable security forces, they confront Wotan the Invincible, a towering quadrupedal robot with a reconfigurable shield array and a slew of powerful weapons, in a large testing area. Late in the battle, Wotan reveals it can detach its upper portion, "Wotan's Better Half", which is capable of operating independently and barraging enemies from the air. After Wotan's two halves are destroyed, Wotan's Brain emerges from the wreckage and futilely attempts to scurry to safety before being eliminated by the Vault Hunter. With Maliwan's most powerful weapon scrapped, Atlas remains safe for the foreseeable future.
- Main article: Takedown at the Maliwan Blacksite (mission)
- The name Wotan translates to Odin in German, fitting the general Norse mythology theme of the raid.
- Wotan may drop the following items (on any Mayhem Mode, including no mayhem):
- In addition, Wotan may drop the following items only when mayhem 4 is active. Each is also dropped by at least one other enemy outside of Midnight's Cairn: