Climate/Terrain: Any land except artic
Frequency: Very rare
Organization: Group
Activity Cycle: Any
Diet: Acid/Flesh
Intelligence: 3-7
Treasure: Nil
Alignment: Special (See Below)
No. Appearing: 1-3
AC: 1
Movement: 16
Hit Dice: 6+3
Thac0: 13
No. Attacks: 2/round
Damage Att. 1d8+acid damage
Special Att: Acid globe, Acid Wave, Incoporation, special
Special Defenses: Only hit with +1 or better, special
Magic Resistance: Nil
Size: 5'-7'
XP Value: 1,500
Morale: 20

The Acid Zombie was created by a wizard who used to dabble in alchemy. Noticing how the properties of acid could greatly enhance the power of a spell, he began to mix acid with some spell components to see what the results would be. After a few minor successes, he decided to see what acid would do to an animated corpse. So before animating a corpse, the wizard (named Ad Plamya) mixed bat guano and HCL acid together and poured them into the corpse's mouth. The then raised the infernal creature. The corpse stood up and began not to decay, but to regenerate its flesh! Then the flesh began to liquidfy and flow around the creature like melted skin. The very sight of an acid zombie causes a horror check in most characters!

Combat: The acid zombie is a very deceptive and powerful entity in combat. There are several reasons for this. The first reason is that its enemies may not even know that they are fighting an undead. The acid zombie can control the fluidity of its skin for some time (up to 30 minutes at 2 hour intervals). Also, the thing is usually intelligent enough to assume the guise of a normal person. However, the one dead giveaway to an acid zombie is its mouth. Because the acid/bat guano has to be injected into the mouth, the creature's mouth has no tonuge. Thus, it can only moan in unintelligable syllables. But the thing, when it is in the guise of a character's friend, may not have to speak to get close to the hated living human... 
In addition, acid zombies have several special attacks. The first attack is acid globe. The zombie, if it is within 5 yards of its enemy, can summon all of the acid on its body to its hand where it shoots out and envelops the enemy. The acid always takes the form of a gigantic globe which completely swallows its victim. If the person fails a saving throw against spells, he is caught in this globe and suffers 2d8 acid damage plus 1d4 suffucation damage. If left in the globe for 4 rounds, the character dies. If the character saves, he suffers only normal acid damage (1d8). Yet acid globe leaves the zombie defenseless, for when the acid is surrounding the victim, there is no acid left on the body and the creature can be hit with any weapon at AC 10. If the zombie takes more that 20 points of damage, it will drop the globe and attack someone else. 
Another attack is acid wave. With this, the zombie builds all of the acid up in the mouth and spits it out. The spit at close range doesn't cover much surface area (only 2 feet). But at long range, the acid is allowed to grow (the acid replenishes itself) and will cover 7 feet. This acid does 2d8 damage first round and 1d8 second. This attack also leaves the zombie defenseless. The acid will replenish itself in time (3 rounds with new acid forming and the old acid flowing back to its master). A person can save against breathe weapon for half damage.
Another attack is incorporation. The zombie shall envelope a person within 2 feet of it within its acidic form. This allows the zombie to grow and feed off the life energy of the character. The zombie also gains one HD. If left in 3 rounds, the character will die. No matter what, the character will temporarily lose one hit die for every round left in the zombie. These heal back at one hit dice returning in one week. The zombie also looses the HD after one week. 
The last special attack comes from the acid. The acid will resort to normal acid in two rounds and will only cause 1d4 damage per round (after the 2nd round). However, when the acid hits a character with an acidic appendage, the damage of the acid is 1d8, for it only covers a small portion of the body unlike the other acid attacks. In the second round, the acid will cause 1d6 damage and will then rsort to 1d4 every other round. The acid also burns through armor in 3 rounds (5 if metal). 
The acid zombie has several special defenses as well. Like most undead, acid zombies can only be hit with +1 weapons. If normal weapons hit the acid, the melt within 2 rounds. Magic weapons have to roll a check. If the weapon rolls a 1, it is destroyed on sight. But if it rolls a 1, it will always be impervious to the acid. In addition, because silver is a very pure metal, it will disintegrate at the acid's touch (because it is so corrupt) if it touches the acid three times. If it hits twice, it will do the same amount of damage rolled on an inferior die (such as a silver longsword will now be rolled with a d6 instead of a d8. But the character will not know this). Yet if a half-silver and half-metal weapon hits the zombie, it will do 1 1/2 times normal damage.
Acid zombies are also immune to death and charm magic, but not illusion and cold. Cold does double damage against acid zombies because it destroys the foul acid on its body.

Habitat: Acid zombies live anywhere except artic regions. Acid zombies also like to travel in groups of three, but never any more than three. If so, they will begin to attack each other immediately. When the zombies travel in three, they form an equalateral triangle with two zombies in the front and one in the back. 

Ecology: Acidic Zombies are not natural undead (if there really is such a thing). Instead, they are the favorite toys of high level wizards and liches. Although they are unnatural, acid zombies have to eat. They have to have a regular diet of acid (preferable hcl) and of flesh. If not, their acid will stop to reguvinate and will dry up. The zombie will then decay and wither away in a matter of hours. Flesh can keep the zombie in tact, but the acid will always be dissolved. 
Acid zombies are intelligent and will often try to manipulate mechanical devices and spells. In fact, one lich equipped two acid zombies with a sinister cantrip spell and an arquebus...(sp)
Source: johnsont1@tiger.hsc.edu