You’ll likely find some Infernal Iron in Baldur’s Gate 3 before you know what it’s used for. It’s worth quite a bit, so your first instinct might be to sell it for a tidy profit. However, this game isn’t afraid to make an important item seem mundane and vice-versa, so what’s the best thing to do?
Where to use Infernal Iron in Baldur’s Gate 3
You need to use Infernal Iron to help repair Karlach’s infernal engine in Baldur’s Gate 3. So, you should not sell it.
As stated above, you’ll likely find a piece or two before you even meet Karlach, in which case you might have sold it. However, if you made this mistake, you should be able to return to the merchant who bought it and purchase it from them.
The Hellion’s Heart, Karlach’s companion quest, centers around you repairing her infernal engine using Infernal Iron, and pieces of this materal are rare and limited. So, you’ll want to hold onto it whenever you find it.
To get this quest rolling, you need to recruit Karlach. To do so, you’ll need to find her on The Risen Road northeast of the Blighted Village. You’ll need to fight the false Paladins and defeat them. After that, she officially joins the team.
After that, you’ll need to go to Emerald Grove and look for a Tiefling named Dammon. He’ll examine Karlach’s infernal engine and discover that it’s killing her and needs to be repaired quickly. Unfortunately, you can’t complete the quest in Act 1. He’ll take a piece of Infernal Iron and perform a minor repair, but you’ll need to meet him in Baldur’s Gate to progress further.
So, needless to say, you don’t want to sell Infernal Iron in Baldur’s Gate 3 if you want to progress Karlach’s questline. If you’re not interested in having her around, then it doesn’t really matter.