Before starting the quest Fiends In High Places, you should wrap all of your side quests and companion tasks. When you begin this mission, the game takes you to Greater Tranquility Station and you cannot go back afterwards. The companions you take on this quest really matter, especially Niles, because his history with Augustine de Vries makes the encounter much more intense. In addition, your prior handling of Seer Wiley alters the makeup of the enemies you can encounter in this mission.
Exploring Greater Tranquility Station

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You will begin at the landing zone which is located right outside Augustine’s ship in the hanger. If you have the Scrapper perk, you can interact with a couple of items on the ship. Inside the station, you will have to fight soldiers sworn to de Vries, or you can experience a little bit of skill check fun and gather information.
First Section

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In the first section, enemies and automechs are found. You can utilize the Greater Tranquility Station Targeting Protocol to force the automechs to attack her soldiers. Alternatively, if your Hack skill is high enough, you can completely disable the automechs and loot the area with no risk. You will acquire a keycard from an Order traitor to unlock additional areas. Additionally, if you have a high Observation or if you have Tristan with you, you may notice a hidden door, which holds valuable loot.
Second Section

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This section does not have enemies, so you can take your time to explore. You will find various lockers and cabinets that will have items like the Ryan Powell Pitchball Card and access to the Vendor Mech who sells various hacking items, including the Advanced Decryption Key installment and the Black Hat. If your Lockpick skill is high enough, you can obtain these without using credits. One additional threat to watch for are Verachnid mines inside one of the powered rooms.
Final Section

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You walk through a long corridor illuminated by red light and filled with large machines. Enemies will spawn at a distance, so once you go up the stairs. Long-range weapons and as much hacking of the automech bays to cut down reinforcements will make things a lot easier to navigate. There is a fuse puzzle that can be solved with Tactical Time Dilation, and after that, you will kill your way through waves of enemies until you attached the elevator to confront de Vries.
Confronting Augustine de Vries

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In the last room, you overheard delegates arguing about continuous peace. Augustine gives the rationale that the rifts represent a direct threat to the Arcadia system, and only the Order, a sanitized Order only, can control the rifts. If you decide to side with Augustine, she kills all the delegates and finishes peace talks, but allows for her vision of rifts to occur in the future.
Escape and Rewards

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Following your choice, the station’s rift becomes unstable. It starts to disintegrate. Quickly retrieve some loot, specifically de Vries’ sniper rifle, The Simplifier, a top-tier sniper rifle with no damage fall-off and distance. Make your way back to your ship using some new escape routes while the station collapses.
