After you beat the Sepulchre, you can enter a place called Miridian's Pass. Once inside the area, follow the right wall. You will find a trail that leads up into the mountains to a statue called "The White Lady". Equip Sangaril with a crossbow and enter first person view. Aim at the colored gongs in a specific order to raise the bridge up to the statue. Once you get there, you will get 15000 experience points. Shoot the gongs in the following order.

First bridge: Red, Yellow, Blue
Second bridge: Orange, Green, Yellow, Red
Third bridge: Blue, Orange, Red, Yellow, and Green