Adventuring through the woodlands, I have mostly cleared the area and found traces of all the missing adventurers except the rogue. I have found a door that I can't seem to open...it's got a hint that it requires a combination of arcane, divine, and valor...when I try to open the door it says there's no path to it, I can't target it with even a knock spell...I feel like I'm missing something obvious but it hasn't come to me yet. The pillars nearby seem to be related, but interacting with them hasn't seem to do anything either. I assume the rogue is located in here somewhere?

Hoping someone can shed some light.