Note that you need to do this quest to get the 4 related diagrams so you can then craft them for part of the achievement, I Wore Ofieri Before It Was Cool.
To start this quest you need to either talk to the Ofieri merchant, Dulla kh'Amanni, at Upper Mill or find one of the untranslated Ofieri diagrams. These are spread throughout the world, but the easiest one to find is during the side quest Rose on a Red Field. When you come across the first group of soldiers quickly take care of them and inspect the cabin. Open the chest on the right side to find the trousers diagram.
If you haven't already talked to Dulla, go talk to him now and ask about the diagram and he'll explain they'd been stolen. He'll then give you information on where he was attacked, so head out to this marker to investigate.
At the site, you will find a set of footprints. Follow them slightly up a nearby hill, until the trail goes cold. Walk a bit up the hill with your Witcher Senses and it won't take long to find a pool of blood. Now follow that trail to a corpse further up the hill. When you investigate the corpse, the trail goes cold again. Walk past the corpse on the left to pick up the footprint trail again. Not too far ahead is a hidden door beneath some hay.
Open the door and climb down into the secret lair. Slay the Fallen Knight that hide out down below. If you are having trouble with the shield carrying knights, use Axii to stun them so you can land a blow or two. With the Fallen Knights out of the picture, use your Witcher Senses to find the chest you need to loot. Inside will be the next diagram and a note. Read it to learn the other camps' positions.
The rest of the quest plays out the same between the two remaining camps. Ride to them, clear them out, loot the chests. Note that the number of enemies you need to defeat increases so be prepared to take on 10-15 knights at the remaining locations.
When you have collected the remaining two diagrams, ride or fast travel back to Dulla to have him translate them. He says it will take one day's time. You can go off and do other things or just simply meditate for one full day and claim your reward.
- If Geralt finds one of the diagrams before talking to the Ofieri merchant:
- While wandering the Redanian borderlands Geralt happened across some crafting diagrams written in a foreign tongue. He supposed the language was Ofieri, but, not being a linguist, he could not be certain. Wanting to resolve this mystery, he decided to look around for Ofieris, having made the indisputable deduction that where there are Ofieri documents, there must surely be Ofieris as well.
- Who would have expected Geralt to come across a camp of Ofieris somewhere on the Redanian frontier? Yet life can be surprising – travelers from a land far across the sea had indeed chosen to pitch their tents in just such a place. The new arrivals had come to gain knowledge and give gifts, but, since life can be unpleasantly surprising as well, they were attacked and robbed by locals. When Geralt heard about this, he felt sorry for the foreigners' loss and decided to help them retrieve their belongings. Malicious types might claim he only did so to get the crafting diagrams he'd been promised as a reward, but I am not among their number and do not believe that for one instant.
- After a great deal of searching, the witcher found the stolen diagrams and delivered them to the merchant as agreed. The merchant repaid him with gratitude and copies of the diagrams translated into a tongue local craftsmen could understand.
- If a diagram is found before talking to the merchant:
- Find someone who can speak Ofieri.
- Find all the diagrams from the Ofieri gear set and return them to the merchant to be duplicated and translated (0/4)
- Look for the place where the Ofieri merchant was attacked.
- Use your Witcher Senses to search the site of the attack.
- Use your Witcher Senses to follow the bandits' trail.
- Search the bandits' hideout.
- Read the letter you found.
- Search the remaining bandit camps.
- Return the diagrams to the Ofieri merchant.
- Wait one day for the merchant to translate the diagrams.
- Collect the translated diagrams from the Ofieri merchant.
- The letter in the bandit's hideout could possibly not be in the chest. Unfortunately the bug still exists and you can't complete the quest.
- As the last patch to fix any game issues was released in 2016, there is no further official patch to fix this bug if one still experiences it. The only workarounds have been to try a new game or a standalone playthrough of the expansion to see if it works then.
- If this mission bugs out on you and you cannot see the wagon and dead horse at the start of the mission near the place the merchant was attacked you may have to reload to an earlier point before paying the 5000 to the Runcrafting merchant.