Infernal alloy is the only type of infernal metal that appears once in bg3. I've tried taking it to dammon but he seems completely uninterested. Presumably it had use with the rest of her quest that was planned for the upper city.
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. I already made everything he could make in. On a related note, in act iii you can get enriched infernal iron.
Infernal alloy, enriched infernal iron; Infernal iron is a metal superficially similar to iron produced in the nine hells. If you destroy the steel watch foundry every steel. Used for karlach' s infernal engine upgrades.
Infernal iron is used in the questline for karlach. If one waits until act 3 to obtain the best quality chunks, does. Infernal iron is a rare material in baldur’s gate 3, which you will need to complete karlach’s companion quest and to forge weapons and armor, so you’ll want to have it in your. There is no use for it currently.