The Baldur's Gate 3 Infernal Iron item is a rare metal that you'll occasionally find in chests and treasure troves across the world. What's it for? Well, as you might gather from the name, this material plays a big part in Karlach's companion quest, The Hellion's Heart, which sees you repairing the engine in her chest.
While you should find a fair bit of Infernal Iron if you're treasure savvy, it's more comparable to Soul Coins in terms of its rarity, so it can be helpful to have a few collected already if you want to progress the quest. Here, I'll run through the Infernal Iron locations I have so far, plus who you need to see about fixing Karlach's engine.
Baldur's Gate 3 Infernal Iron locations
There are lots of different places you can find Infernal Iron in the Forgotten Realms, but here are all of the ones I've found so far:
- Blighted Village: This is likely the first Infernal Iron you'll find. In the basement of the north house, where you find the forge and start the Masterwork Weapon quest, you'll find a chest if you climb up the ladder. Open this to get a piece of Infernal Iron. Be careful of opening the trapped explosive chest below it first, however, since it can potentially blow up the ladder.
- Zhentarim Hideout: This smuggler hideout is tricky to find, and I detailed the elaborate process of how to get inside in our Underdark entrances list. Once inside the hideout, head to the north end of it to find two locked doors with some wolves and guards nearby. Unlock the leftmost door and pick the lock of the right-hand chest to find the iron.
- Shattered Sanctum: You can find a second piece of Infernal Iron in the Shattered Sanctum in the Goblin Camp. Head to the far north, behind where Dror Ragzlin is sitting, and unlock the door to get at the loot. There are also a lot of great magical items in this pile, and the good thing is if you're killing all the goblins, you don't have to worry about getting spotted.
- Grymforge: If you speak to Stonemason Kith and pass all three checks when examining the scenery, he'll give you a piece of Infernal Iron.
- The Gauntlet of Shar: On the west side of the gauntlet, just before you head through the door into Balthazar's workshop, there's a difficulty rating 30 locked door just to the north. Crack this open and loot the chests inside for some Infernal Iron.
- Yurgir: If you defeat this demon in the east wing of the Gauntlet of Shar, he'll drop some Infernal Metal. I haven't found another purpose for this type, so I have a feeling it might just function the same way Infernal Iron does.
- The Mason's Guild: In the main courtyard of the Mason's Guild to the south-west of the Last Light in the Shadow-Cursed Lands. You can find a piece of Infernal Iron on a workbench.
- Steel Watchers: In the Lower City in Act 3, you can loot Infernal Iron and Enriched Infernal Iron from many of the big Steel Watcher robots that patrol the streets. You'll have to fight a fair few of these at the Steel Watch Foundry in order to blow it up, but after you do, every Steel Watcher in the game will collapse, letting you loot them for any Infernal Iron they have.
What is Infernal Iron used for?
Infernal Iron is an important part of Karlach's companion quest. As you might know, the Tiefling barbarian has an infernal engine inside her, and while it makes her a great fighter, she does run a little hot. If you go and visit the Tiefling smith, Dammon, in the centre of the Emerald Grove settlement, he'll explain that the engine is actually going into overdrive and will kill her, unless you repair it with some of the rare metal, Infernal Iron.
You'll need to locate some and bring a piece back to Dammon. He'll repair Karlach a bit and then tell you to meet him in Baldur's Gate later in the story, by which time he'll have more solutions to Karlach's problem. You can then find Dammon again during act 2 at the Last Light Inn with the other Tieflings, where he'll accept another piece of Infernal Iron to repair Karlach fully.
It's also worth noting that if you Save the Emerald Grove and you haven't spoken to him with Karlach and started the quest to find the Infernal Iron, Dammon will leave for Baldur's Gate. On the opposite side, after you raid the grove, you won't be able to repair Karlach with Infernal Iron or talk to Dammon.
Infernal Alloy and what it does
You can also buy Infernal Alloy from Stonemason Kith in the Grymforge and this version of the metal has a special function. If you bring this to Dammon at the Last Light Inn, he'll forge you the Flawed Helldusk Armour set, which deals fire damage to enemies that hit you. You can get the proper Helldusk Armour later in the game as a Legendary item, though it's unrelated to all this Infernal Alloy stuff.