Ghost in the Cemetery (Silver) - Get through Scotland cemetery combat encounter without killing or being seen
During Chapter 8, you will be able to explore inside of Avery's grave and once you finally come out, there will be an encounter with some enemies (this is the Dormitories one on the Encounter menu). Start off by going to the left side, as shown in the video, and start climbing the walls. You will want to be careful of the one enemy that looks over the edge, as he can spot you if you're right underneath him.
Your goal in the first part is to climb up to the top section, where you will find a beam that you can use to jump to the portion right next to the door. Once the enemy has his back turned, jump and grab the upper left, then go to the left to hide from any patrolling enemies. As long as the enemies' meters don't turn orange, you're okay. While hanging from the ledge, wait for the coast to get clear, then quickly make your way to the door to open it with Sam's help. If you get caught, you can simply reload the last checkpoint without worrying about having to redo the entire encounter from the beginning.
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