Under Cover of Night
From Halopedia, the Halo wiki
Under Cover of Night is the tenth piece included in the Halo: Original Soundtrack.
The music consists of a slow synth melody with a more complicated bass line interweaved. The melody continues with a variation before entering a bridge to the original melody. There are no drums in the music until the initial melody enters, before which the bass provides the rhythm. After the equalized drum beat is added, occasional chants can be heard. The piece ends with a drum solo.
The track can be heard:
It was rearranged into the following: