To Kill a Demon

To Kill a Demon is the eighth track included in Halo 3: Original Soundtrack, and plays during the Halo 3 campaign level Tsavo Highway. It is composed of To Kill a Demon (0:00-1:05), Ancient Dust (1:05-2:07), Punch Through (2:07-2:58), and Underestimated (2:58-3:42).

To Kill a Demon (1:05) begins with ambiance invoking the atmosphere of a dry desert. Low strings enter, playing a heavy melody as a low-strings-only version of To Turn a Tide (from the track This is Our Land), but soon fade out as the ambiance take over completely. This piece plays when John-117 and his Marine forces defend their position against Type-52 Phantoms after crossing the broken bridge.

Ancient Dust (1:02) fades in with heavy percussion and low strings playing the triplet rhythm from the Halo Theme in repeat. The percussive beats and low strings crescendos into a series of cymbal clashes to end the piece. The piece plays during the encounter with Type-26 Wraiths at the cliffside overlooking the Portal at Voi.

Push Through (0:51) begins with digital notes and sound effects playing in soft ambiance. The short piece ends as vocals and strings take over the digital sounds effects to transition into the next section. The piece plays during the final encounter of the level, where John-117 defeats a Jiralhanae pack led by a Jiralhanae War Chieftain at the tunnel entrance leading into Voi.

Underestimated (0:44) features the percussion from the track Farthest Outpost, opening with muted drums, then leading into percussive beats played using snare drums and hi-hat. High strings enter with the melody of Under Cover of Night, though the piece ends after one phrase of the melody. The piece plays during the ending cutscene of the level, in which Miranda Keyes reports to Lord Hood.

Trivia
The name of the soundtrack alludes to "Demon", the title the Covenant has given to Spartans, and may be a reference to the book To Kill a Mockingbird by Harper Lee.