Unspeakable Horrors

 is a Challenge Banner in Fortnite: Save the World, that can be earned by killing 20,000 Mist Monsters in successful missions.

Tips

 * If you are trying to obtain multiple Challenge Banners, it is recommended to do the Play with Others Mission to help achieve more than one banner at a time.
 * Mist Monsters are often found in higher zones such as Canny Valley and Twine Peaks. It is recommended to play objective missions such as Destroy the Encampments and or Eliminate and Collect. Side quests inside of missions such as completing a Storm Chest will guaranteed atleast 2 Mist Monsters.

Trivia

 * The Unspeakable Horrors Banner is one of the toughest banners to achieve in Fortnite.
 * The Unspeakable Horrors Banner rewards a Silver Achievement for consoles and is Ultra Rare with a 0.1% completion rate.