https://www.polygon.com/fortnite/2018/9/28/17913928/fortnite-hunting-party-challenge-legendary-skin

Fortnite Season 6 is here and it brought with it a new season-long challenge for players to complete called, Hunting Party.

Just like the Blockbuster and Road Trip challenges before it, each step of the Hunting Party challenge requires players to complete all of the challenges that open up on each week of the season — that’s seven total challenges each week. Once players have done this seven times they’ll unlock a hidden legendary skin. Because you need to have completed seven full weeks of challenges, this mystery skin won’t be available until week seven of the season.