Spinebreaker key

[Mark I]

I have gone mostly through the temple of order, and just met up with Deadeye. He ran away from me and I walked up the hallway to find a dead body with a key. I think the key opens the door to the north of the hallway, but it doesn't work. I think this door leads to Batlin, but I can't get through. Any ideas?

[Paulon]

Use the key which Selina dropped when she abandoned her ambush...