Repository

At the start of the mission, defeat the Sentinels patrolling the bridges. The Sentinel Beam is effective, and fallen Sentinels drop ammunition. Ammo crates are also available.

Proceed across the bridges to a darker room with a central terminal. Two locked doors with red lights are on platforms.

Interact with the terminal to trigger a cutscene (a non-interactive cinematic the game plays automatically). After the cutscene, defeat the Banished that emerge from the doors opposite. The red lights on the doors will turn blue, indicating they can be opened.

Take a power seed from one room and place it in the crucible in the other room.

To reach the room with the power seed, jump to the platform and use the Grappleshot to pull yourself the remaining distance.

Take the power seed and use the Grappleshot again to reach the other side. Sentinels will attack; you can either drop the power seed to fight them or try to outrun them.

Once the power seed is placed, an energy barrier in another room will deactivate, granting access to the Grunt Birthday Party Skull.

Continue through the door marked by the quest marker (use AI Scan if needed). You will encounter Sentinels, Jackals, Grunts, and Elite Brutes. Focus fire on heads to quickly kill Elite Brutes.

Reach a room with a large window overlooking the ring's surface. Turn left from the window and follow the ramp up, killing Sentinels.

In the next room, defeat Skimmers and Brutes, then proceed through the door marked by the objective marker.

In the subsequent room, defeat two Elite Brutes wielding Ravagers and more Sentinels. Look up at the window above two large pillars.

Use the Grappleshot to enter the room beyond the window, where the energy barrier was deactivated. Be extremely careful as the skull is guarded by four Elite Brutes wielding Energy Swords and using Active Camo.

Use Threat Sensor immediately upon entering and use grenades to force the Brutes out of hiding. Stay near the window to keep the Brutes at the back of the room, but watch out for and dodge their grenades.

Once you enter the room with the skull, you will be locked in until all four Elite Brutes are killed. Focus on defeating one Brute at a time.

If you run out of ammo, use the Grappleshot to acquire an Energy Sword from a fallen Brute. You can then use the Energy Sword to defeat other Brutes. After striking, quickly move out of melee range, potentially grappling towards the window or ceiling to allow your energy shield to recover.

After acquiring the skull, follow the objective markers. You will trigger a cutscene near an inactive gravity lift and a terminal.

Use the now active gravity lift to proceed. The cutscene automatically unlocks a UNSC audio log titled “The Weapon” (number 4 in Recovered Files).

Ascend the gravity lift and defeat Brutes, Jackals, and Grunts in the following rooms.

Reach a larger room with two unpowered crucibles. You need to place power seeds in these to proceed.

Find the power seeds in the rooms beyond the doors and down the ramps. At the end of each ramp, you will encounter two heavily armored Elite Brutes. Throw grenades and use high-damage weapons immediately to inflict maximum damage.