One of the biggest changes added to Fortnite in Season 6 is the introduction of a new consumable called Shadow Stones. Using one allows you to transform into your Shadow Form, which gifts you with a couple of supernatural powers. [Update: Shadow Stones were absent for much of the first week, as Epic was forced to pull them due to an exploit. They've since returned, and just in time, as using them is one of the Week 2 challenges.]
In Shadow Form, you won't be able to use weapons, but whenever you stand still, you'll go completely invisible. You'll still be slightly visible whenever you move in Shadow Form, and walking around leaves behind a Shadow Trail that people can easily follow. Running around isn't all that bad though, as you'll have increased movement speed and jump height, and you won't take fall damage.
The true fun comes in your other supernatural ability, Phase. Using Phase propels in whichever direction you're facing. If there's something in your way, like a rock or a wall, you'll pass right through it. With Phase, you'll be able to easily escape anyone who discovers your Shadow Trail, or scare someone with your ghostly apparition in an ambush.
Shadow Form only lasts up to 45 seconds--and can be ended early by holding down the Alt Fire button--so you'll have to figure out when's the best time to use a Shadow Stone after you've found one. Shadow Stones randomly spawn around the map, but can usually be discovered in corrupted areas.
Fortnite Season 6 also puts Impulse Grenade, Suppressed Submachine Gun, Light Machine Gun, Bouncer, and Remote Explosives into the Vault. Grapplers have been updated so that connecting to a moving object incorporates its momentum into your launch force, and the charge for Grapplers has been reduced from 15 to 10.
Fortnite is available for Xbox One, PS4, PC, Nintendo Switch, Android, and iOS.