#Dungeon23 Tomb of the Vampire Queen, Level 12, Room 6

 Once the doors to this tomb are open, the party will see a hallway with many alcoves. When the party enters the hall, green slime begins to pour in.

This slime looks like Green Slime and has many of the same properties, but this is Necrotic Slime. Instead of eating flesh, it eats "life."

Necrotic Slime

Armor Class: 10
Hit Dice: 12* (54 hp)
Attacks 1 × touch (consume life energy)
THAC0 8 [+11]
Movement 3’ (1’)
Saving Throws D6 W7 P8 B9 S10 (12)
Morale 12
Alignment Chaotic
XP 2,700
Number Appearing 1 (0)
Treasure Type None

The slimes can reach 5' with a pseudopod. If the Necrotic slime touches a character, it drains 1 level or 1 point of Con (GM's choice).  

They can be destroyed by fire and are immune to lightning attacks. 

There are four Necrotic Slimes here.