Amoral Combat

Amoral Combat is a side quest in the Fallout 4 add-on Nuka-World.

Detailed walkthrough
After completing The Grand Tour, the next time Nuka-Town is visited, a gang member will inform the Overboss that a new challenger has reached the end of the Gauntlet, and they should go talk to Fritsch to find out what to do.

Locate Fritsch in the Nuka-Cade. He will say a new target has entered the Gauntlet, and gives two options: allow them through to the arena, or drive them out. Driving them out prevents acquiring whatever gear the challenger has, but finishes the quest right there. Accepting a fight means the player has to face the challenger and beat them.

If you choose to fight, head to the Cola-Cars arena, meet the foe, and best them to maintain the title of Overboss.

This quest is repeatable, with a new challenger every time, culminating in the Rogue knight, who, upon defeat, will drop the unique weapon Aeternus.

Bugs
The quest may not start as intended.
 * To fix this, try to return to Nuka-World using the monorail and go through the Gauntlet again.
 * It can be fixed by using the console command.