The first image is a concept drawing of an unnamed creature. How this demon will be attacking you is up to your imagination for now.
Official Blizzard Quote:
"While this ... thing resembles the Khazra, its form is twisted and distorted. It would only be one of many instances where the denizens of Sanctuary have been risen or reformed for demonic purposes."
The second picture is a screenshot from the King Leoric Torture Chambers dungeon that we've seen previously, of the Witch Doctor using his http://diablowiki.com/Firebats" class="wiki-link">http://media-diablofans.cursecdn.com/attachments/16/736/wiki2.gif" alt="DiabloWiki.com - Firebats"/> Firebats skill. You can also see one of the Zombie Dogs aiding in the Witch Doctor's fight against the demons. Notice the giant axe-type apparatuses that swing down damaging anyone in its path.
Click the images to bask in the glory of the high resolution versions that you likely won't see anywhere else! 25,000 more likes to go until the 900k mark where we can get some more images, and 5 more milestones until we hit the 1 million 'Like' goal. Go visit facebook.com/Diablo and 'Like' the page to speed the war effort!