There is 1 Dead Ghost to be found in The Legion's Keep. They can be collected on any mission or during a patrol. Each Ghost can only be collected once per account.
Ghost 1[edit]
Head for the massive spire that is marked in the photo. Thisis your marker.
Head into the area underneath the spire:
Look along the left-hand side part of it. On the ground, in this portion, you will find the Dead Ghost: