Neathiron is one of the most important crafting materials in Diablo 4 Season 11, especially if you want to Masterwork or Sanctify your gear and reroll or push Greater Affixes on your best items. Unlike more common resources like Forgotten Souls or Obducite, Neathiron drops in smaller amounts and only from specific high-end activities, so you can't just grind anything at random. If your goal is to fully upgrade multiple items or try different builds, knowing the best Neathiron routes early will save a lot of time and frustration Diablo 4 Items.

Farming Neathiron is mostly tied to harder content, so you'll need a character capable of clearing mid- to high-level Nightmare content and handling boss fights efficiently. Treasure Breach Nightmare Dungeons, world bosses, and certain summoned bosses are the primary sources, and the most efficient approach is to combine several of these rather than relying on just one. Following a consistent loop also helps you pick up other resources like Obducite, Scrolls of Restoration, and Betrayer's Husks while you hunt for Neathiron.

Treasure Breach Nightmare Dungeons are generally the most reliable source. These dungeons require special Treasure Breach sigils, which you can craft through the Occultist or earn from world bosses, overworld events, and certain chests. A well-run Treasure Breach can give about 10–15 Neathiron per run and also provides a large amount of other crafting materials and loot, making it the cornerstone of a Neathiron farming routine. Many players focus on Treasure Breaches first and then supplement with other sources when sigils run low.

Targeted boss farming is particularly useful once you have a strong damage build. Using Betrayer's Husks to summon bosses like Belial can net one to three Neathiron per fight, and adding specific essences, such as purified Hellfire-type essences, can increase the overall efficiency. This method works best when you already have a stockpile of husks or when your build is strong at single-target damage and quick boss fights.

World bosses and other high-tier activities also drop Neathiron, though they're not as efficient as Treasure Breaches or dedicated boss loops. They can provide Treasure Breach sigils or direct Neathiron drops, making them useful to run between your primary farm activities. Even if the yield is lower, these activities help keep your resources flowing and prevent downtime.

For the most efficient approach, think in terms of a farming loop rather than isolated runs. A solid loop in Season 11 might involve using world bosses and overworld events to collect sigils and boss materials, running Treasure Breach Nightmare Dungeons as your main source, and spending Betrayer's Husks on targeted boss fights like Belial to top off your Neathiron. 

Along the way, you'll naturally gather other crafting resources, allowing you to Masterwork and Sanctify gear steadily instead of saving everything for a single big session cheap Diablo 4 materials. This kind of loop turns Neathiron farming from a grind into a structured endgame routine that supports both your character progression and your gear upgrades throughout the season.