Eridium is a resource in Borderlands 4 that can be obtained and used in various ways. Guides are available that provide information on how to get and use Eridium, as well as where to spend it, although the specifics of its use are not entirely clear. The game's endgame details, including Ultimate Vault Hunter Mode and dedicated drops, have also been discussed, but it is unclear how Eridium relates to these features.