This is Leonidas Returns from the Halo 3 OST.

It´s the last track on the song called Three Gates.

Credits to Davin Eastman for the orchestal arrangement and roddypatooty for post and twesks.

Te rar file contains a MIDI and a pdf.

The difficulty for me is 6/10 in a 85% of the song, and 8/10 in the other 15%.

NOTE:
If you have problems with the rar file try using 7-zip or WinRAR to open it.