The second volume in Dark Horse's Richard Corben Library.

The book is very nicely printed on heavy stock.
The image size of each page is identical to the three previous English editions, Ariel, Catalan, and Fantagor
The pages have much more detail because of using the original art
The whole book is re-lettered for consistency by Nate Piekos.

These are the extras:

1- Foreword by José Villarrubia
2- Introduction by Patton Oswalt
3- First Edition Foreword by Fritz Leiber
4- Essay: The Art of Richard Corben by Bruce Jones
5- Gallery section (10 images)
6- Biography of Richard Corben

From the publisher:

The first volume presenting the long-out-of-print masterpiece Den, by fantasy legend Richard Corben!

This special edition also features bonus material, art pages restored by long-time Corben collaborator José Villarrubia, new lettering by Nate Piekos of Blambot, and an introduction by Patton Oswalt, all presented in a gorgeous hardcover with a dust jacket.

Thrust into a bizarre fantasy world called Neverwhere, the muscular adventurer Den goes on an exotic adventure through ancient ruins meeting an evil queen, her sacrificial doppelganger, bizarre lizard men, giant insects, and more strange and dangerous madness in this legendary saga brimming with horror, magic, and violence.

The inspiration for the Den segment of the cult classic film, Heavy Metal!

FOR MATURE READERS

"The artist I most want to aspire to is Richard Corben. His style is visual and it tells the story just as you see it... ...my favorite is Corben. I love everything he does, I love his stuff ...he's an amazing artist."-- Guillermo del Toro

"Richard Corben stands among us like an extraterrestrial peak. He has sat in his throne a long time, above the moving and multi-colored field of world comics, like an effigy of the leader, a strange monolith, a sublime visitor, a solitary enigma"-- Moebius

"Mr. Richard Corben... a genuine giant of his chosen medium."-- Alan Moore

Well known for his legendary fantasy underground masterpieces published by Fantagor Press as well as Heavy Metal, Richard Corben's work has been recognized internationally having been awarded one of the most prestigious recognitions in comics literature the Grand Prix at Angoulême as well having been inducted into the Will Eisner Award Hall of Fame.