Bionis' Awakening

Bionis' Awakening (originally unofficially referred to as The Awakening of the Giant) is Disc 2, Track 12 on the Xenoblade Original Soundtrack and Track 10 on the Xenoblade Chronicles Special Soundtrack. It plays during the cutscene in the Mechonis Core in which Zanza reawakens the Bionis.

It also plays in Xenoblade Chronicles: Future Connected, when the Fog King first shows its form inside.

Trivia
If the game's language is set to English, the chanting at 1:09 will be significantly different from the OST version. (This does not happen if the game's language is set to Japanese.)