Slip's Music Database: MapleStory BGM & OST Collection

Would this happen to be the track you were talking about? (link)
That track was included with the Tempest update and is likely used for Luminous' storyline.

If it's not that track, can you find a gameplay video with the BGM playing so I can take a look?

That track sounds like the Aurora Temple, though yeah that's not the one I'm looking for.

Here's a video where the bgm starts: http://youtu.be/VIb4sSpXb8k?t=31s

While I'm at it, I forgot how amazing Forest of Peace's bgm was. What's the name/where else does this theme play?