By "Dread Necromancer" do you mean that as a title or as the actual class Dread Necromancer? If the latter, you're already using Heroes of Horror, perhaps you should invest in some of the stranger and darker information in that book. Initiate a Taint system as the Necromancer's influence spreads... starting with in the horrors of his backstory lie the risks of taking on some of that Taint by learning Things Man Was Not Meant To Know or something along those lines.
There's a lot in HoH that can take an upbeat campaign and turn it on its head. Unholy Scion is one of my personal favorites - a young child touched by the forces of darkness, which also lays an unbreakable geas over its mother to make her an undyingly loyal (but not always willing) servant. There's an example storyline in HoH involving a Scion, and the ghost of her dead father who's trying to stop her, and some other things. It can get really freaky. If you haven't already done so, it's certainly a place to start.
As for twists on the Necromancer... you can get into some real depravity with undead. Perhaps he discovered a way to bind his undead in such a way that their souls are still on the corpses, present and conscious but unable to control the body or break the necromancer's command... meaning that each undead they slay still is fully aware of its former self and fully aware of the torment it's going through as the players destroy it, while all the while it's body is loyally following the Necromancer's orders and trying to kill the heroes. That's just a start... you can get REALLY nasty with undead if you take a while to think about it.
I could not help myself but when I read you post I though "He is a kitty"
Most mages of the necromantic take over the world type start as a powermad spellcaster. Well not here, our mad-take over the world Necromancer started out life as a tan and yellow kitten. Nothing special or odd with our on day to be mad-man bent on annihilating whole nations here. Just a cute and cuddly kitten who in time would be bonded with a mage named Ovoiliss. He was a noble and kind wizard part of a band of do gooders that come and go and in time like most familiars ours learned and grew and was named "Vasariss" he to grew in power, becoming a boon companion to Ovoiliss until the dark day where they died.
Liches are cruel and vile beasts at time, Ovoiliss died at the hands of one to some lost and powerful arcane spell, Vasariss survived and fled but somehow, maybe from the spell that warped him held onto his mind and somehow held onto a part of Ovoilisses power as well. For weeks he wondered the wilderness half made with the loss of his master and slowly starving. By the time he made it to a town he was a dead thing, and abomination flesh held together with power and possing an intelligence no animal should. He fled into the wild made with vengeance dancing in his head and hunted by those who once his master had called friends, he felt betrayed and for years he was alone in the wild hunter, stalking always trying to improve his power
For years he hunted forgotten ruins, tombs and looting the dead for power, He held with in himself the knowledge of spell craft but with limited body still he hoarded and learned. Then come the day he found the necromancer, he was rotting though a long forgotten crypt when Vasariss found him., stalking him from the shadows and scatting out massages in the dust, the necromancer thought he had stumbled across a ghost and Vasariss had a plane, he though massage's left in dust showed the necromancer how to call forth an undead familiar..unbeknown to the necromancer he was bonding with Vasariss.
Soon the Necromancer left the tomb with a new familiar, one who was both teacher and student. Together they plundered tombs, raided forgotten librarys, and spoke with both the long dead and the demonic. All the while the necromnacer did not know his familiar was far more powerful then himself. In time as the necromacer aged they together crafted a spell that would make him live on, A spell that would jump his spirit from one body to another. AT the hight of his casting however Varasiss betrayed him and once the spell was completed it was Vasariss soul that was freed and his master mind that was subjugated.
Soon after the now human bodied Vasariss put his vengeance in motion, forming army of undead, tricking advanters into plundering the liches tomb and in time destroying what once killed him.
Now the lord necromancer is set to take his vengeance upon the world that turned on him with the power he has claimed over hundreds of years.He jumps from body to body, his army acting as replacements as much as anyone near him, his can flee into the shadow plane at will ..the only way to end this menace is to find the now crumbling cat body hidden long ago and force the soul into what was once his mortal form
But varariss is no fool, long gone from most records is the name Varariss and long hidden is what was once a cuddly kitten taken on by a kindly wizard
How about they gradually discover clues and hints pointing to the conclusion that the "Dread Necromancer" is actually a good guy and the Elven city has been secretly ruled for several centuries by an evil cabal of wizards, directing the society to complete some long-lasting and complicated plot.
By the time the heroes break into the necromancer's stronghold and confront him, they have picked up enough clues to not just kill him on the spot but to hear him out. He may be an ex-member of the cabal, who finally saw the light, repented and turned on his peers. Alternatively, he could play the part of the reformed evildoer - whilst secretly planning to betray the party and take complete control of the elven nation once the stupid heroes have eliminated his rivals.
I could not help myself but when I read you post I though "He is a kitty"
ROFLMAO!! AWESOME!! :D
Glad it amused. I could so see this with clues and hints leading to his now dead necromantic "master" leading the party in a misdirection and maybe letting them find shrine to his long dead true master, hints with in hints
Anyhow it was just a random though I had glad someone was amused as much as I was