This guide details the locations of the three coliseums accessible via the 3C3C1D119440927 DLC in NieR: Automata. This DLC, available in all editions, unlocks after a short period of gameplay, delivering a mysterious letter containing coordinates. These coordinates lead to challenging coliseums with six ranks, each featuring progressively tougher enemies.
Trial of the Sand Coliseum Location
This coliseum is located in the desert. From the "Desert: Center" access point, zoom your camera out and look to the right (facing away from your entry point). You'll spot an orange diamond marking the coliseum's entrance. A machine guards the entrance, but it won't pose a significant threat. Inside awaits the Trial of the Sand Coliseum quest.
Gambler's Coliseum Location
To find the Gambler's Coliseum, begin at the "Flooded City: Coast" access point. Follow the coastal path used to protect the resource ship. At the path's end, look right towards a waterfall. Circle around the building to the left, locating a Resistance member guarding the entrance. A 1000G bribe unlocks access to the Gambler's Coliseum quest.
Underground Coliseum Location
Note: Access to this coliseum is restricted to 9S.
Starting from the "Forest Zone: Center" access point, follow the forest's left edge until you find machines training near a large waterfall. Pass through the waterfall to reach the entrance; only 9S can enter.