Skulltaker Halo 3: Cowbell
From Halopedia, the Halo wiki
You must start this level from the beginning; starting from any other point will cause the skull to not appear. After defeating the Scarab, take a Gravity Lift from the small structure in the center (to the right of the entrance up the large slope), then continue on until you pass the room with a lot of explosive Plasma Batteries. In the hallway after this room, there is a tall section with openings above the turning point of the hall, and the skull is in the top one of the highest of these. There are several methods to obtain this skull:
- Method A: Use the Grav Lift to get there. The ideal place to deploy it is about three fourths of the way down the ramp, and a little to the left of the center, while facing up-ramp (facing up-ramp will ensure the Grav Lift doesn't slip farther down). Run down the ramp and jump, such that you reach the peak of your jump while directly over the Grav Lift. You should also be running towards the tall section, aiming towards the middle of the top shelf on the section. If your Grav Lift expires or is destroyed, you can always revert to last save since the room containing the skull is a checkpoint. If you have difficulty getting there, crouch while being Grav-Lifted. This may take a few tries.
- Method B: If you are having too much trouble placing the Grav Lift, it is possible to drive a Brute Chopper into the building. You can then drive the Chopper to the bottom of the ramp, jump onto it, and deploy the Grav Lift, which will go through the vehicle. You should be elevated to the opening with the skull.
- Method C: If you are playing on Co-Op, have two of the players grab a Grav Lift. One (Person A) should drop their Grav Lift before the platforms, use it to go up to the fourth level (one below the skull), and wait for their partner (Person B) to join them. Person B should stand right on the edge of that platform and deploy their Grav Lift while facing straight down. If Person A placed the first one right, then the two Grav Lifts should line up, with one hovering above the other. Person A should then walk backwards off the edge and onto the Grav Lift(s). A will end up being suspended above the platform with the skull, at which point they should just keep holding the left thumbstick forward until they move onto the platform. If they can't move forward, they should keep pushing forward anyway, because when the lower Grav Lift breaks, they will drop onto the platform.
- Method D: If you managed to pass through the previous room without setting off any of the plasma batteries, push one down to the edge of the openings, detonate it with a plasma grenade or a brute shot, and explosive jump to the top opening.