Since the Colosseum content was datamined a while back it was thought it may come as part of some DLC update.
Today Fromsoftware has confirmed it’s arriving tomorrow, 7 December. The good news is this will be totally free for everyone.
Come forth, warriors, and bask in the glory of the Colosseum.
Prove your worth in various duels and battles, together or on your own in the free Colosseum Update. Coming December 7.#ELDENRING pic.twitter.com/TAq4c0vaG2
— ELDEN RING (@ELDENRING) December 6, 2022
This looks to be a fun PvP addition prior to any major DLC announcement. Perhaps The Game Awards on 8 December will bring some more news on a more substantial DLC update for the future.