A couple things to know,

1 tag is completely missable (Ninian's) and is not added to your inventory if you skip the prologue so you need to play it. Pate's tag is no longer required for the achievement as of 6/6/25.

You should try to turn all of them in at once, sometimes the quartermaster in the keep stops accepting them if you don't. This should be fixed as of 6/6/25 but just be aware.

Credit to the devs who helped me find the one in the flooded mine I was missing.

1. Ninian (Island Asylum) strapped down in the laboratory, have to kill him
2. Pate (jumps off keep wall) find him on the walls of the keep and read the note for him and then tell him the truth and he'll jump to his death later. *AS OF 6/6/25 THIS ONE IS NOT REQUIRED FOR THE ACHIEVEMENT*
3. Right by fingerless colm the bandit
4. By a boulder below the Kings Road bridge
5/6. Both are in the sunken village overworld buildings
7. In hut by redcaps
8. Right outside flooded mine
9. Inside Flooded Mine (underwater near the end, below little bridge that leads to the boss)
10. Left of the lighthouse entrance
11. In the ravine between the keep and the village
12. In the side tunnels in the ancient crypt (entrance across from where you meet the necromancer)
13. Camp near starting beach.