How to Use Eridium in Borderlands 4
The mystical ore called Eridium is central to the lore of the Borderlands series and has always played an essential role in its endgame. This remains true in Borderlands 4, where Eridium is used for several valuable endgame progression and farming purposes.
Main Uses of Eridium in the Endgame
Eridium has three main uses in the endgame of Borderlands 4. Because it can get exceedingly expensive, you’ll need to be judicious about how you spend it:
- Respec your Specializations – Cost: 5,000 Eridium per instance.
- Activate the weekly Moxxi’s Big Encore machine – Cost: 100 Eridium per instance.
- Use the Firmware Transfer machine – Cost: Variable depending on gear.
Respec Your Specializations
Specializations unlock in the endgame as permanent upgrades to your characters that can scale infinitely. Respeccing costs 5,000 Eridium per instance, so it’s important to be intentional about how you spend your Specialization points.
While investing just one or two points may not dramatically improve your character, these upgrades add up over time. Keep in mind that Specializations are build-agnostic, so they won’t benefit every setup equally. If you choose to completely respec your character into a new build, be prepared to pay the 5,000 Eridium cost or risk losing a significant boost in your damage per second (DPS).
Use Moxxi’s Big Encore Machines
Moxxi’s Big Encore machines are a rotating weekly endgame feature. They allow you to fight a select boss again with, according to Gearbox, “an even more rewarding loot pool.” For example, if you want loot from The Bod, you’ll need to wait until Axemaul is the featured Big Encore boss for that week.
Although the cost is only 100 Eridium per use, don’t underestimate it. Even with increased drop chances, you could easily spend 10,000 Eridium without obtaining the desired items. That’s just how RNG works in Borderlands.
Spend Eridium on Firmware Transfers
The Firmware Transfer machine is the third primary way to use Eridium. While you might not use this machine as often as the other two methods, it can still consume a significant amount of your Eridium. The cost varies depending on the type of gear you are transferring firmware to. Frequent use can quickly deplete your Eridium reserves.
How to Get More Eridium in Borderlands 4
Most missions in the game award some Eridium, and killing Vile enemies and world bosses provides additional amounts. However, the most effective way to farm Eridium is by completing Vile Bounties.
You unlock access to Vile Bounties after activating Ultimate Vault Hunter Mode. These bounties task you with hunting higher-difficulty Vile enemies scattered across the overworld. Each kill grants a modest but meaningful amount of Eridium instantly—typically several hundred while leveling, increasing as you progress deeper into the endgame.
Another way to farm Eridium somewhat efficiently is by completing weekly Wildcard missions. While these do not yield as much Eridium per hour as Vile Bounties or base patrols, they provide a steady stream of resources if you can complete them quickly.
It’s likely that an activity with a much better Eridium farming potential will be introduced within the first few DLC cycles. This will be necessary, as Borderlands DLCs have historically added increasingly powerful Legendary items throughout a game’s lifecycle, making Eridium an even more valuable resource.
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