Domineering

You MUST be playing as Richtofen to activate this quest.

Reach Round 15 and, using Melee Macchiato, punch a barrel in the Core Foundry to open it. Afterward, hold interact on the barrel to begin digging to eventually reveal the Ritterkreuz awarded to Richtofen during WWII, which once picked up will teleport you into the quest, showing you the truth of Richtofen's past.

If you have the Mocha Maul augment for Melee Macchiato equipped, you'll need to obtain the Jotunn Star and melee the barrel with that instead to open it, or restart your game without that augment. Save & Quit seems to be broken for this quest.