I woudn't get your hopes too high; it's likely a mistaken prepublication placeholder or a paperback that was in the pipeline before Night Shade went belly up.

Night Shade's as dead as a doornail, but the corpse has been raised an imprint by it's purchasers, Skyhorse Publishing and Start Publishing.

From: Marc Rikmenspoel <marcrik@gmail.com>
To: Glen Cook: Science Fiction/Fantasy Author <glencook-fans@mailman.xmission.com>
Sent: Thursday, August 22, 2013 11:00 AM
Subject: Re: [Glencook-fans] SEQUEL DESPERATELY NEEDED!!! : Wicked Bronze Ambitions

Meanwhile, Working God's Mischief has an Amazon release date of March 11, 2014. They also show a trade paperback of Sung in Blood to be released on May 6 next year. The publisher is listed as Nightshade(!), so they not be completely dead after all. It gives me hope there could be the eventual release of an omnibus of Wrath of Kings. I'm anal retentive, and want one to sit evenly on my shelf with A Cruel Wind, A Fortress in Shadow, and An Empire Unacquainted with Defeat!