So, why do so many fantasy RPG worlds and their descendants among paper and computer RPGs have huge cemeteries and crypt complexes when all the bodies just keep clawing awake as zombies and skeletons in huge numbers salted by assorted nastier undead monsters? Why don't these societies just take up cremation of the remains and prevent getting overrun by slavering hordes of ancestors? Are they peculiarly stupid?
It could be that the whole undead thing is a new phenomenon, the whole basis of the typical zombie apocalypse movie genre where either the dead rise or the living get infected, die, and stand back up the next day hungry for brains.
But a lot of game worlds have undead as a long term thing in the background. These places have been haunted by the cursed minions of necromancers and liches forever.
My current thought is that cremation does not prevent the rising of the dead, it makes the situation worse.
Instead of hordes of mainly manageable zombies and skeletons, you get more incorporeal undead if the culture cremates the dead. This could be garden variety spectres and wraiths, nasty enough to dissuade you. Or maybe its worth introducing some new undead to a campaign that includes this as a world premise. So far I just have a name, and a flavor for them in mind, not stats and mechanics. Maybe describing an encounter will sort it out...
In a place afflicted by the curse of undead rising, the Ashen are what you get when the ashes of the cremated rising instead of corpses or bones. That pile of ashes your doughty barbarian is dragging through with his dagger, looking for hidden gold? Yeah, they swirl up in a whirlwind, and coalesce in the air into a malevolent shadowy form with glowing eyes that reach out and strangle him, as gouts of ash flow into his eyes, blinding, his mouth, choking, and nostrils, asphyxiating. His mighty blade, swung in blind panic, cleaves the being again and again, but it reforms immediately. Another rises and confronts the wizard. A couple of syllables into his first spell, and he has to stop, as the first ash into his throat has him coughing and gagging, and he has to close his mouth tight against it and run for all he's worth, hoping to get away before his held breath runs out. The dwarf quickly ducks through an open door, and spikes it behind him, unfortunately its into a dead end room and there's ash flowing in through the cracks beneath the door and around the edges. He doesn't have long to come up with a new plan before the one that flows in will attack.
Just writing that out as the scenario came starts to suggest mechanics. They should take magic weapons to harm, as is traditional for the more serious, less corporeal undead. Around 5 HD for the basic ones seems about right. They are not energy level drainers, instead they control the fight by blinding and incapacitating. It takes one combat round to pass through crevices, and another to gather back together into a combat capable form. In the dissociated form, it can fly on the wind, and generate its own breeze to travel in still air.
Each time an Ashen hits, it gets one of the following effects:
Ash flowing into the victims eyes blinds and causes excruciating pain. So the target is both afflicted by whatever your rules give for blind fighting penalties and a pain penalty of -2 on actions. This is not just a flung handful of sand, it is animate crud, that is actively scoring the eyeball, but, as it is D&D, a save vs petrifaction, or a Fortitude save in later flavors, made in a subsequent round will remove this effect. It also does a D6 of damage initially and a point per round. Moving fast while blinded should include a high chance of disorientation, probably ruled off the cuff.
Ash flowing into the mouth & nose requires a save vs poison or a tough concentration check DC20-ish , or penalized spell casting roll (-4 or so on a D20), depending on the game's spellcasting mechanics to be able to complete any spell being spoken in the round struck. Besides that, it chokes and makes speaking at all very difficult. Take a D6 of damage and make a save as above for the eyes. Success means holding one's breath in time and only suffering a -2 penalty and ending an ongoing 1 point of damage per round. Failure means -4 penalties on all actions, being busy attempting to breath, coughing terribly, and choking. Asphyxiation can be assumed as the source of the damage and penalties.
Those ongoing damage points will stack, with a save needed versus each hit to halt them all. One saving throw per round.
Ashen can also quench torches and lamps with hits, deface open scrolls, flow into and ruin potions opened by melee combatants they are fighting, manifest enough solidity to pluck away items that are not firmly held in hand, like arrows in quivers and sheathed weapons, dump pouches, etc. Losing initiative to Ashen in melee contact probably means you're screwed that round as far as using scrolls or potions. Given an ashen one such minor action in addition to its normal attack on any round in which it has initiative.
Ashen are immune to fire damage. Magical winds and strong natural winds can keep them at bay or disperse them for a period of time, depending on the strength and duration of the wind. Swift flowing water is another natural defense that can carry them off and disperse them for a time.
5 HD undead monster
Base move 9"
AC 2 vs magical weapons
Number appearing 1-8
% in Lair 40 - mostly lying around in piles or in urns when encountered. Ambush predators. Surprise on 1-4 in first encounter. Subsequently, normal odds of surprise.
Could also be met as a breeze wafts ashes along the floor of the tunnel that was previously still.
Dousing with holy water damages them for 1D6, and is a touch attack (AC9 effectively).
Treatment of ash injuries with a vial of holy water will halt the effects of one ongoing hit, as will magical healing like a cure light wounds, in addition to the damage points healed. Cure serious wounds and similar more powerful magics can all ongoing damage over time hits at once, and end the penalties from them.
[I need to make an editing pass on the Ashen, and trim it down a bit. Inventing as you go and trying to account for too many alternate mechanics in places gets wordy.]