This is really good! I like this!
This sounds like a RPG battle theme, where the player fights some acid-spitting spiders in a castle basement.
The piano plays really well in the beginning. Then it keeps on playing calmly, as if a decision is to be made. The cymbal swell and horns then arrive to keep you reminded in what situation you are in.
Then the choirs starts to sing as if the player or the enemy took action. It's brilliant!