The first DLC for Assassin's Creed Odyssey, The Fate of Atlantis, is free on all platforms this weekend.
According to Ubisoft's website:
From August 26th to September 1st, we're giving away the Fields of Elysium, first episode of The Fate of Atlantis DLC, for FREE.
Discover the paradise of Elysium and what sinister secrets are hiding behind its beautiful façade.
As well as getting the DLC for free, you can buy the season pass for 50% off:
The Season Pass includes the full Legacy of the First Blade and Fate of Atlantis story arcs plus Assassin's Creed® III Remastered!
The Assassin's Creed Odyssey base game is required to access season pass content, including the Fields of Elysium episode.