Primus Or'sek, Vessel of Nightmares

Primus Or'sek, Vessel of Nightmares is a powerful Cabal Centurion Nightmare under the control of Emperor Calus. It is encountered on board the Derelict Leviathan as part of the Nightmare Containment Public Event.

Gameplay
Primus Or'sek serves as the Tier 2 boss of the Nightmare Containment Public Event. If you are successful in completing the first three waves, the massive Centurion will spawn at the Nightmare Harvester. Or'sek comes equipped with a Projection Rifle, which can fire explosive munitions at long distances. If players get too close, it will unleash a powerful stomp attack, sending anyone within range flying backward and potentially causing significant damage. The boss is also extremely durable and can withstand a lot of punishment. Picking up Unstable Essence from killing other Nightmares or having other teammates participating can help to wear it down faster. Upon losing a half of its health, however, Or'sek will be protected by an immunity shield, preventing you from dealing any further damage. Players must destroy all four Resonant Splinters that located in the air around the Nightmare Harvester in order to lower the boss's defenses, after which, you may return to fighting it. If players manage to kill the Vessel of Nightmares before time runs out, Tier 2 of the Public Event will immediately come to an end, but failing does not make a difference in terms of moving on to the final round.

Trivia

 * Despite mostly having the appearance of a Red Legion commander, Or'sek's armor is decorated with same golden ornaments present on Loyalist gear. The helmet it wears is a combination of the Centurion and Legionary designs, whilst also baring the same horsehair-like crest that Phalanxes have.

List of appearances

 * Destiny 2
 * Season of the Haunted