Luminous Arc: The Tension (Extended)
A ...Well, tense battle BGM from the game "Luminous Arc".
Now this is something a little more suited to a combat scene. The fact that it first plays during what could be considered the game's first true boss battle (I'd call the unique enemy in chapter 3 more of a mid-boss than anything else), works well in establishing that this is where the long haul starts and it's time to get serious.