I tend to look for another type of zombie. They shouldn't necessarily have a stench, as that would make them easier to track via creatures with Scent (such as dogs). Also, in the dark it gives warning of their presense (albeit not their location). They should also have more resistances to damage and immunities, and I tend not to like new mechanics (although I did have to add one to deal with body parts still able to move about and attack - as well as being severable in the first place without a vorpol weapon - as the rules do not make cases for called shots or this unique form of spawning). The disease bit was a nice idea, although I altered that a bit too:
[sblock="My revision of Green Slime's variant Zombie"]
Flesh Eatting Zombie
Size/Type: Medium Undead
Hit Dice 2d12
Initiative -1
Speed: 20 feet (4 squares, can’t run)
Armour Class: 9 (-1 Dex) touch 9, flatfooted 9
Attack: Claw +2 melee (1d4+1) or Bite +2 melee (1d3+1 + 1 Str + Disease)
Full Attack Claw +2 melee (1d4+1) or Bite +2 melee (1d3+1 + 1 Str + Disease)
Base Attack/Grapple +1/+6
Space/Reach 5ft./5ft.
Special Attacks: Create Spawn, Disease (DC 11, 1d6 Dex damage & 1d4 Con damage), Restoring Bite (+1 Str damage)
Special Qualities: Daylight Sensitivity, DR 10 / Bludgeoning, DR 5 / Slashing, Cold, Piercing, & Sonic Immunity, Acid Resistance 5, Electricity Resistance 20, Fire Resistance 10, Life Sense, Single Actions only, Turning Resistance +2, Undead Traits, Vorpal Vulnerability
Saves: Fort: +0, Ref: -1, Will +3
Abilities Str 12, Dex 8, Con --, Int 3, Wis 10, Cha 1
Skills: -
Feats Improved Grapple
Environment Any
Organization Any
Challenge Rating ??
Treasure None (Incidental)
Alignment Always Evil
Advancement None
Create Spawn: Any victim of the Disease of the Flesh Eatting Zombie whose Dex or Con is lowered to zero by the Disease dies only to rise again 1d4 minutes later as a new Flesh Eatting Zombie.
Daylight Sensitivity: The Zombie is weakened by the harsh sunlight, suffering -2 to all attacks, saves, ability and skill checks, and -1 to all damage rolls. Due to this it often actively seeks dimmer lit regions, rarely coming out in the day light unless no darkness or shade can be found. In nature this often means caves and forests. In towns this usually means sewers, cellars, and deep inside the larger, most poorly lit, buildings.
Life Sense: Auto-detects general direction towards any living creatures within 30 ft, but cannot target precise distance (and thus cannot determine precise location / square).
Restoring Bite: Every bite attack made by a Flesh Eatting Zombie against a living creature of flesh causes 1 point of temporary Strength damage. The Zombie regains 1d4 hp from the bite.
Single Actions only: Can only take one action per round: a movement action or an attack action.
Vorpol Vulnerability: While the Flesh Eatting Zombie is immune to extra damage from critical strikes, a critical strike made with a slashing weapon that deals enough (normal) damage to overcome its DR also severs an appendage from the zombie's body. Any successful strike with a vorpol slashing weapon that deals (normal) damage beyond the DR threshold similarly lopps off an appendage - regardless of whether or not the strike is critical.
When such happens the appendage continues to attack on its own. Its hp is limited to 1d2 - which permanently lowers the zombie's by a similar amount. If the zombie's hp is 2 then each has 1 hp. If the zombie's hp is 1 than the appendage does not animate. The appendage has a speed half that of the zombie if an arm and a quarter that of the zombie if a leg or head (rolls). If the zombie loses one or more legs its speed is reduced to half as it pulls itself along the ground.
Flesh Eatting Zombie Template:
Str +2, Dex -2, Con --, Int -8, Cha -8
Bonus Feat: Improved Grapple
DR 5 / Slashing
DR 10 / Bludgeoning
Immune: Cold, Piercing, & Sonic
Resistance 20: Electricity
Resistance 10: Fire
Resistance 5: Acid
Turning Resistance +2
Create Spawn (those that die due to disease rise again 1d4 minutes later)
Daylight Sensitivity (-1 dmg, -2 all attacks, saves, etc)
Disease (1d6 Dex damage & 1d4 Con damage, DC 10 + half HD)
Restoring Bite (+1 Str damage to victim & +1d4 hp to Zombie)
Life Sense (30 ft)
Single Actions only (single move or single attack action each round)
Undead Traits
Vorpal Vulnerability[/sblock]
I considered adding SR, but I thought that might be a bit much. Also, what should I make it? SR 4 or 5? A flat SR 10? Often the SR is based on the CR (an odd mechanic for it), but I am not certain what CR to give this creature. Even one would be a problem for a party of less than second or third level - perhaps CR 4 or 5?
In any case, with or without SR, this is a major problem for any community. Imagine one of these secreted into a sewer system in a major city (perhaps 10k+ members). Within a few days there will likely be dozens more of them. Within a month anyone who hasn't left has likely been transformed, especially as each bite attack is a new initial infection, and eventually higher HD persons will fall to them - if for no other reason than being ganged up on. These will, of course, have a higher DC disease. To explain why these things have not overwhelmed the landscape I would suggest having them occur recently in a highly out of the way and difficult to reach location.
One that comes to mind is a large town in a mountain landscape. Every winter the single passage leading to it is buried in snow. Now the snow has recently melted, but no trading merchants have come out of the passage. Parties sent in to check on the town do not return. Perhaps, very recently, one of the undead has wandered out of it. It was destroyed, but several others died in the process. Many think it was a ghoul (no ranks in Know Religion to realise the differences) and the PCs have been called to go deal with an infestation of ghouls that is believed to have blocked the route to the town - perhaps even begun attacking it from within.
It would be better yet, of course, if the PCs were one of the original parties going in to investigate, told that it is likely bandits or some natural disaster has prevented the townsmen from traveling through the pass. Their job is to deal with the bandits or - if it is a natural disaster - help the townsmen recover so that trade can be restored (perhaps an important mine - gold, gems, etc - is next to the town, perhaps the PCs might be well rewarded if trade can be restored, and moderately rewarded if they return with news if trade cannot be restored).
They go in - not expecting undead, let alone these monsters. They have to navigate a landslide that makes travel difficult, and perhaps they have to deal with some goblinoid warriors near half way through the pass. They think they've dealt with the problem, but perhaps they capture a prisoner (who doesn't speak their language, but very obviously seems more interested in leaving the pass than waylaying the party). Little by little it becomes more apparant that something it terribly wrong. Perhaps the landslide openned a sealed cavern where a necromancer experimented for decades before being slain by adventurers - his lair collapsing immediately after the fight. Now freed, the zombies wander along the easiest path (ie: not blocked by the rest of the landslide) and end up encountering the town. The PCs arrive to find what seems to be an abandoned town. Then night falls while they are deep within it, and shuffling sounds announce the return of the town denizens.
Of course, a few might still be alive - hidden in obscure locations, half starved and terrified almost to the edge of insanity. Perhaps the party encounters one - just as the sun begins to set . . . .
Needless to say, this type of adventure can be a lot of fun, but it would be best to have the party a level or two higher than what you expect is necessary to win - if for no other reason than they will not go in expecting to fight undead, and so they may be terribly unprepared.