Valor Mortis All Eternal Guard Locations (Oathbound Side Quest)
This guide will show you where to find all 7 members of the Eternal Guard in Valor Mortis.
Defeating them rewards you with pyramids. Once you have all 7, you get the Mysterious Stone Slab, which lets you open the door in the Fortress to finish the "Oathbound" side quest and get the 
We Wear the Same Colours trophy.
None are missable, and they can all be defeated after finishing the main story.
Eternal Guard #1
The Battlefields > Onslaught Arch.
From the lantern, backtrack until you reach a fork in the path. Stick to the right path around the camp. You will then come to another fork where 2 enemies are. Here, take the left path and hit the growth on the wall with your pistol or rapier to destroy it. On the other side you will find the Eternal Guardist.
Eternal Guard #2
Fallen Village > Marketplace.
From the lantern, turn around and backtrack through the wagon. Before heading through the shortcut in front of you, head left. Here, pull out the growths (you get the ability to do this later in the story) and wall run through the next area. At the end you will enter a cave, where you will find the Eternal Guardist.
Eternal Guard #3
Valley of Ashes > The Climb.
Ride the lift next to the lantern up to the top and then continue along the cliffside until you reach the part with enemies on the wooden structures under the large bridge. After this you will see a path leading up and to the right. Don't head up that path. Instead, look for another green path below that follows the cliff to the right. The Eternal Guardist can be found at the end of this path.
Eternal Guard #4
Caverns > Old Mine.
Follow the main path into the next room, where you use the lever to raise the crate and then your Stasis Transmutation to stop it halfway up (just like you did on your first visit to continue on the main path). Now stand on it and disable the Stasis by interacting with the cogs to ride the crate up. Jump off to the right and follow the corridor to find the Eternal Guardist.
Eternal Guard #5
Cursed Hollow > Village Church.
From the lantern, head through the shortcut right next to it that takes you directly to the open fields you used to get to the church (if you don't have it, follow the main story path until you reach the church). Then go straight ahead, heading slightly to the left. You will find the Eternal Guardist behind a house surrounded by hay.
Eternal Guard #6
City of Orphans > Shamble Street.
Head through the gate shortcut next to the lantern to get to the waterfront. Here, head left into the area with the tall enemies, then straight through the poison area (you will need the Shield Transmutation, obtained from the University later in the story). Follow this path through the alley on the left and then through the building to come out on the other side of the growth, which you can destroy with a node from this side. Here, head left to find the Eternal Guardist.
Eternal Guard #7
Fortress > Courtyard.
Head through the arch on the left of the courtyard (the main story path), then head left and defeat the red-eyed enemy. The Eternal Guardist himself is dead on the floor next to this enemy, and you have to loot the items from him.
Once you have defeated all 7 and have the Mysterious Stone Slab, go to the opposite end of the corridor from where you defeated the red-eyed enemy for Eternal Guard #7. Here, examine the symbol on the wall to open a secret room. Inside, examine the note on the table to finish the quest. Remember to loot the chests around the room.
