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Aeternus is a unique weapon in the Fallout 4 add-on Nuka-World.


Aeternus is a unique Gatling laser that bears the Never ending legendary effect.

Although it uses the "Never ending" effect, its actual effect gives the weapon true unlimited ammo. It will use a portion of a fusion core when first fired, but the core's charge will not decrease again while using Aeternus.



Carried by the rogue knight during the quest Amoral Combat. The quest must be repeated until the rogue knight is the challenger. Upon their defeat, they will drop Aeternus.

Related quest


When firing the Aeternus with a fresh fusion core, the shown ammo will always become one less than all the fusion cores in the player character's inventory. The remaining charge of the active fusion core is not equivalent to this number. If the maximum number of fusion cores in the player character's inventory is one, the ammunition in the clip will become zero, causing the fusion core to deplete and be removed from the inventory. As such, the Aeternus is nearly completely useless when having less than three fusion cores in the inventory. Additionally, if the amount of fusion cores in one's inventory increases while the Aeternus is out, the current fusion core will instantly be consumed and the gun's ammo will become equal to the remaining fusion cores in one's inventory, then decrease by one when firing the Aeternus again.

Behind the scenes

The weapon's name is from the Latin language, meaning "eternal" or "immortal."


  • Playstation 4Playstation 4 Consumes 33% of a fusion core on the first shot, then nothing for the rest of its use. If the gun is put away or switched, it has a new fusion core automatically inserted which takes another 33% of the cores charge on its first shot. This can leave a regular user with a large stack of fusion cores with only 67% charge. Once the player is out of full-charge fusion cores the gun will automatically load the partially depleted cores, which will then fully deplete the fusion cores, though they still function in the gun.[verified]
    • To fix this, keep all but one fusion core stashed on a companion or in a container.
  • PCPC Playstation 4Playstation 4 Xbox OneXbox One It seems to be irregular in consuming ammo. Sometimes draining a fusion core entirely in the first shots, or firing only as many shots as the player has fusion cores and then removing one core entirely. [verified]
  • PCPC Used cores randomly deplete to under 10 power then switch to a new core. As the ammo counter shows how many cores one has this is misleading as it gives the appearance of having infinite cores, until one sees all their cores have anywhere from 3-9 uses left. [verified]
  • PCPC Playstation 4Playstation 4 After killing the rogue knight, it is possible they drop a random legendary item. [verified]
    • This can be avoided by forcing the rogue knight to exit their power armor, pacify and then fire at them, they will now be using the weapon, however it may not be legendary.
  • PCPC If the user has one or two fusion cores in their inventory, Aeternus will fire off one or two rounds before fully depleting the equipped core. If one has at least three fusion cores, the fresh loaded weapon will almost drain the equipped core completely on its first shot, after that it will reach "unlimited ammunition", consuming no charge afterwards. This is valid up until one loads a new fusion core either by equipping another weapon, modifying the Aeternus in a weapons workbench, or increasing the amount of fusion cores in one's inventory.[verified]