One Final Effort
From Halopedia, the Halo wiki
300px One Final Effort is a song included in the Halo 3: Original Soundtrack. It is heard on the level The Covenant when you face the two Scarabs. It is the third movement of the Covenant Suite
It starts with a piano playing the theme from This is the Hour. It then switches to the music from the Halo 3 version of the Halo Theme. The end is a soft string melody that fades to a close.
It runs for 3 minutes and 8 seconds.