Gravity throne hologram
From Halopedia, the Halo wiki
This is a glitch in the level Delta Halo. Armed with a ghost, The_Delta_Halo_Vacation, and a lot of patience, you should be able to reach the end of the level. However, no honor guards will spawn and attack you, and the hologram prophet that Cortana translates, is gone. The Gravity Throne is still there. No idea why, but it's a glitch.
