NieR: Automata's 3C3C1D119440927 DLC unlocks three challenging Colosseums. After receiving the Mysterious Letter, you'll need to locate these arenas to unlock unique rewards. Note that the Underground Colosseum is only accessible as 9S.
Quick Links
Trial of the Sand Colosseum
This Colosseum is situated in the desert. From the "Desert: Center" access point, look to the right (facing away from your entry point) for a distinctive orange diamond-shaped structure. A machine guards the entrance, but it won't pose a threat. Inside awaits the Trial of the Sand Colosseum quest.
- Rank S Reward: Destroyer Outfit (A2)
Gambler's Colosseum
Located in the Flooded City, access this Colosseum from the "Flooded City: Coast" access point. Follow the path towards the coast (the same route used to protect the resource ship). At the end, locate a waterfall to the right. Circle around the building to the left, where you'll find a Resistance member guarding the entrance. A 1,000G bribe unlocks access to the Gambler's Colosseum quest.
- Rank S Reward: Revealing Outfit (2B)
Underground Colosseum
9S ONLY: This Colosseum is accessible only when playing as 9S.
Start at the "Forest Zone: Center" access point. Follow the left edge of the forest until you encounter machines training near a large waterfall. Pass through the waterfall to access the Underground Colosseum quest.
- Rank S Reward: Young Man's Outfit (9S)