30 Day Challenge: Day 23 Least Favorite Monster

This is kind of a tough one...

I think Haunts from the Rules Cyclopedia. I really disliked how insanely powerful they were, making it impossible to use ghosts as low level monsters. Because of that I wrote up a much lower level haunt: Restless Spirits

Slimer
Armor Class: 2
Hit Dice: 4** (M)
Move, Fly: 120' (40')
Attacks: 1 touch
Damage: 1d6+special
No. Appearing: 1 (1d4)
Save As: C4
Morale: 8
Treasure Type: Nil
Intelligence: 7
Alignment: Chaotic
XP Value:

Monster Type: Undead
Slimers are a really nasty type of focused, Non-Terminal Repeating Phantasm, or a Class 5 Full Roaming Vapor, as classified in Tobin's Spirit Guide. They are universally gluttonous and spiteful beings. They attack by flying through their target and "sliming" them, which causes 1d6 points of damage, and on a failed saving throw will paralyse the target for 1d6 rounds, in addition to covering them in ectoplasm. Slimers ignore armor when attacking. In addition to the usual undead immunities, slimers are incorporeal, and immune to normal weapons.