The final boss of the Ghosts of the Deep dungeon in Destiny 2 features several throwbacks: Oryx's body, Deepsight nodes, and Hive rituals. All this comes together in a mechanically simple, yet threatening boss fight that tops off the Lucent Hive-themed dungeon of Season of the Deep.
Simmumah Ur-Nokru is like most Hive wizards in Destiny 2, so players will likely now have any issues with her movement. That said, she has a few tricks up her sleeve, including sending a swarm of moths after the players which can quickly one-shot a guardian. Here's how Simmumah can be defeated in Ghosts of the Deep's third and final encounter.
Ghosts Of The Deep: Defeat Simmumah Ur-Nokru, Lucent Necromancer
The rally banner is right at the front as players enter the arena where Oryx's body is being resurrected by the boss. Like in Ecthar's encounter, this encounter also has underwater sections and overground sections, though players will only need to traverse underwater to get to additional rooms in the cave system the boss encounter takes place.
Start off by destroying the ghost by Oryx's head to begin the encounter. Somewhere in the arena, a Deepsight node will have spawned. When players interact with it, they'll be able to spot three locations around the arena where black dots are hovering and a green ritual circle is highlighted on the ground. These three circles will be connected to each other with green lines.
Stand on one of these ritual circles to gain the Ritual Conductor buff. A Hive knight named Vorlog, Risen In Heresy, will spawn somewhere nearby. While standing in this ritual circle, defeat him to move the boss to that specific circle.
Once Vorgol is down, two symbols should now be hovering in the air: a Hive face symbol, and a circle. Players must position themselves so that they can look through the circle towards the Hive face symbol. This usually means moving into a different ritual circle on the arena.
Doing this reveals the required Hive rune for that specific ritual circle—there are three in total for each phase. To find these ruins, players need to access the underwater cave doors around the arena and look for them. It might take some time to do this, but the encounter is not timed until players pick up a Vestige, so there's no rush.
The cave splits off into three different rooms, where the respective Hive symbol is hovering over a group of enemies and a Lucent Lightbearer. Defeat the Lightbearer to pick up a Vestige, and return back to the central arena.
While carrying the Vestige, pick up the Deepsight buff from a node again and then head over to where the respective matching symbol is located to bank the Vestige. Once all three are banked, the ritual circles will turn into those green pools similar to the previous encounter, which will grant players the Piercing Light buff. Like with Ecthar, the buff allows players to destroy the boss' shield. A message stating she's vulnerable will appear when the shield has been expended.
After one damage phase, the process restarts again. Simmumah does quite a bit of Arc damage, so players are encouraged to run double, even triple Arc Resistance mods for this encounter, as well as heavy ad-clear. The boss likes to teleport around the arena during the damage phase, so be ready to deal damage to her even from afar. Linear fusion rifles can be good for players who are confident in their aim—otherwise, machine guns or rocket launchers can also be used. Be also aware of the moths that can easily sneak up and deal a lot of damage to players.
Destiny 2 is available on PC, PlayStation 4, Xbox One, PlayStation 5, and Xbox Series X/S.