After defeating Sepulchre, head over to Miridian's Pass. Once inside, follow the right-hand wall. Follow the trail up into the mountains and you'll find the statue of "The White Lady". Equip Sangaril with a crossbow and enter first person mode. Aim at the colored gongs in the correct order to raise the bridge to the statue. Once there, you recieve 15000 experience points. The order of the gongs is as follows:

Bridge One: Red, Yellow, Blue
Bridge Two: Orange, Green, Yellow, Red
Bridge Three: Blue, Orange, Red, Yellow, Green