The Delirium skin is an Epic Fortnite outfit. Delirium was available via the Item Shop for 1500 V-Bucks and you can buy it from Fortnite Item Shop when it will listed.
Fortnite Delirium Outfit Details
Don't worry, it's only a nightmare...
Fortnite Delirium Outfit PNG Images
Here is the PNG images of Delirium below!