https://www.polygon.com/fortnite/2018/10/24/18017966/fortnite-patch-6-20-notes-change-list-fortnitemares

The new Fortnite patch has a massive amount of content to explore. While some of the patches so far this season haven’t been so big, patch v6.20 makes up for all of them with one of the biggest patches the game has ever seen.

The biggest addition in this patch comes via the game’s Halloween event: Fortnitemares. Instead of a normal limited-time mode, this is going to be a limited-time event, which completely changes every single game across all of the different Battle Royale queues. Fortnitemares is adding new AI enemies to the game, as the Cube has come back to haunt players and is sending its minions after everyone. Killing these enemies will give players loot, but it looks like they do present some danger.