Death Weavers is the fourth book in the Five Kingdoms series, released on March 15, 2016. It is preceded by Crystal Keepers and succeeded by Time Jumpers. Its events are set mainly in the echolands and partially in the kingdom of Necronum.
Trapped in a world where magic is powerful and dreams are real, Cole’s epic adventure continues in book four of the New York Times bestselling “fanciful, action-packed adventure” series (Publishers Weekly, starred review), from the author of the Fablehaven and Beyonders series.
Cole is about to face his biggest peril yet.
Since arriving in the Outskirts, Cole and his friends have fought monsters, challenged knights, and battled rampaging robots. But none of that has prepared them for Necronum.
In this haunting kingdom, it’s hard to tell the living from the dead, and secret pacts carry terrifying risks. Within Necronum lies the echolands, a waystation for the departed where the living seldom venture.
Still separated from his power, Cole must cross to the echolands and rely on his instincts to help rescue his friends. With enemies closing in, Cole risks losing everything to find the one thing that might save them. 
- Although it says in the official description that "within Necronum lies the echolands", it's the opposite that's actually true, as the Outskirts was revealed to have been built in the echolands. Necronum is merely the location where the physical Outskirts meets the echolands.