Infernal Iron isn’t the rarest item in Baldur’s Gate 3, but it doesn’t exactly grow on trees. You’ll need two pieces to advance Karlach’s companion quest. You can take any spare pieces you collect to Dammon, who will help you forge it into some powerful armor.
All three acts provide you with an opportunity to find Infernal Iron. Ideally, you’ll collect at least two pieces by the time you reach Act 2. Then you’ll be able to fix Karlach’s Infernal Engine and progress her quest enough for its dramatic conclusion in Act 3. If you’re having trouble hunting for rare minerals along the Sword Coast, we’ve got you covered.
Act 1 locations
There are four different places you can find Infernal Iron in Act 1. First, head to the basement of the northernmost house in the Blighted Village. Clear out the calcified web blocking the entrance to the basement and jump down the hole. Don’t open the first chest you see, or you’ll burn the ladder you need to get to the Infernal Iron. Climb the ladder, and your prize awaits you.
The next piece is a bit harder to obtain. You need to find the Zhentarim Hideout, which is northwest of the Waukeen’s Rest waypoint. The hideout’s residents won’t willingly hand over the Iron, so you either need to kill them or steal it. It’s locked inside a chest that’s on the other side of a locked door at the northwestern end of the hideout.
The third piece of Infernal Iron is hidden inside the Shattered Sanctum, where the goblins have set up their camp. Dror Ragzlin has the piece of Iron locked inside his stash. You’re free to use whatever method you prefer to get into the stash and claim the Iron for yourself.
Finally, your quest for Infernal Iron will take you to the Grymforge. Stonemason Kith is holding onto this piece of Iron, but he’s not unwilling to part with it. If you pass a few skill checks talking about the stonework of the Grmyforge, a very impressed Duergar will give you the Iron for free.
Act 2 locations
Act 2 has one of the easiest pieces of Infernal Iron to obtain in the entire game. The only thing you need to do before getting it is find a way to walk through the Shadow-Cursed Lands unscathed, and you need to do that to progress through the act anyway. The Infernal Iron is just sitting on a bench in the Mason’s Guild, ripe for the taking.
The last two pieces of Infernal Iron that you can find in Act 2 are both in the Gauntlet of Shar. Balthazar’s Vault, which is just outside of his laboratory, holds one of the pieces. Getting into it requires an incredibly high 30 lockpicking check, though a magical workaround like the Knock spell will also work. You can obtain the other piece while progressing Raphael’s quest. After killing the challenging boss Orthon Yugir, the Infernal Iron can be looted off his body.
Act 3 locations
By the time you reach Act 3, you’ll probably have very little need for more Infernal Iron. The good news is that if you need more, it won’t be hard to find. You can actually loot Infernal Iron off fallen members of the Steel Watchers. They put up a mean fight, but the closer you get to level 12, the easier they should be to defeat.