While the Grymforge has several Duergar mercenaries and Deep Gnomes who are unhappy with where they currently are, one Duergar named Kith is fascinated with the fortress.
Upon exploring Grymforge, you may stumble upon this stonemason who is looking at the remarkable architecture of the fortress.
He asks for your help as he needs you to lend your eyes to help him discover more about the Grymforge with the use of your observation skills.
Where To Find Stonemason Kith?
Stonemason Kith can be found near a destroyed wall in Grymforge, which will be near the area where you dock the Duergar Boat.
You may find him by heading straight towards the waypoint and taking a turn to the right where you will find him walking around. (He is marked on the map with a merchant icon)
How To Help Stonemason Kith?
Once you speak to Stonemason Kith and agree to help him, you will be presented with 3 choices which are History, Investigation, and Perception Checks.
You will need to pass all these checks one by one to get a reward from Kith and just getting one Ability Check wrong will alter the results.
This makes it necessary to do a Quicksave whenever you are successful and load it whenever you fail the next one.
Rewards From Kith
If you manage to pass all the Ability Checks when making observations, Kith will reward you with an Infernal Alloy that he mentions he had found.
Should you fail to pass even one of the Ability Checks, you will not get the Infernal Alloy from him for free, but you can still purchase it from him afterward.
Verdict
Stonemason Kith mentions that he prefers to avoid violence and focus on his observations, being one of the few friendly faces you see at Grymforge.
Choosing to pass the Ability Checks and report your observations to Stonemason Kith is a good way to get an Infernal Iron as there are only a limited amount of these in the game.
If you decide to assault the Duergar at Grymforge and end up fighting Kith, you can always loot the Infernal Alloy from his body if you end up killing him.