Golem co-op (they won't attack each other), with owner and hit point displays in orange text and messages when the golems die
Confuse spell which acts like Hellfire's berserk, making monsters fight each other
Precognition spell which shows the true name and ID features of dropped items (rogues have this automatically!)
Shakedown spell which gives a chance of a monster dropping two items instead of just one when they die
Shrines have a 5% chance of misfiring, casting teleport on you
Artifacts which act as portable shrines, usable when you wish it
Emperor's prefix which can inflict quadruple damage, but has a chance of healing a monster
Promotion suffix which improves qlvl of drops by 4 for normal monsters and by 2 for unique monsters
Monster display includes how many hit points are left

And many more suffixes, prefixes, spells (a Telekill spell, woohoo), monsters, graphics, and sounds.  It looks like a great mod with vast improvements over the original.  And you'll like Wirt.  I promise that.  :)  Go and check out the full list of features and download Netherworld here.