Caverns of the Valiant (Heb Sed)
An enemy encampment in Heb Sed. You'll raid the place during the Follower or Leader side quest.
Use the bushes and/or ledges by the entrance to kill or sneak your way in.
Veer right toward the hidden passage marker. Again, use the shrubbery to sneak or sneak-kill past the guard.
Slip into the catacombs.
Follow the passage to slightly larger sarcophagus room (the same room with the Ankh, if you're on the Follower or Leader quest. The first location treasure is a carbon crystal box here.
Exit through the small square passage west.
Scale the cliff there for a shubberied vantage on the camp commander.
Assassinate him, and proceed west, where the other officer and treasure are. Use the pillar tops to snipe or dropkill the captain.
When you have a clear shot, drop down the squarish hole the captain was guarding.
Loot the red chest there to complete the location.