The latest content update added a free multiplayer mode to Ghost of Tsushima, bringing plenty of people together to slaughter countless Mongol invaders, for one whole week now. The team at Sucker Punch counted over two million matches since the game mode launched, and now the studio is preparing for the final step (before taking on new adventures). The last challenge that awaits only the most experienced samurais, opens its doors on October 30, when the raid "The Tale of Iyo" will finally become available.
Before you throw yourself into this end-game challenge, you and your buddies should have completed the nine episodes, because, according to the developers, the raid serves as a continuation of the co-op story that two players can enjoy together in Ghost of Tsushima: Legends. Finishing them once won't be enough, though, since you need a high equipment level in order to not slow your comrades down. Sucker Punch recommends a minimum KI of 100 (and that should still be a real challenge). Furthermore, matchmaking is not available for this activity, so you have to organize your squad yourself.
Source: Sucker Punch.