https://www.gamespot.com/articles/overwatchs-halloween-terror-event-returning-with-n/1100-6462173/

Halloween Terror is returning to Overwatch for the third year in a row. Blizzard is still keeping the exact details about this year's Halloween-themed event under wraps, but the developer has provided a hint in the form of a cryptic riddle. [Update: Blizzard has now revealed the first new Halloween skin, which gives Doomfist a new look.]

This year's Halloween Terror starts on October 9 and continues through to October 31. Once the event ends, you'll have to wait until 2019 to unlock Overwatch's Halloween-themed content. The only clue we have as to what this year's Halloween Terror will include and where Junkenstein's Revenge's story will go next is a poem and short cinematic included in one of Overwatch's tweets.