Chaotic Psychoplasm

Hail Chaos, lord of all.

HD 10
AC as leather (it actually shifts constantly and rapidly, but this is the average, so use it)
Attacks (see below)
Movement (see below)
Save 10+
Morale 10

Pure chaos flesh barely contained by our feeble laws of physics.  Surface appears as liquid skin, so eyes, mouths, teeth, hair, fingernails, nipples, and genitalia all swim across its surface.  Its interior "biology" is similarly amorphous.  It is mindless, incredibly aggressive, and has no control over its abilities.

I love that this gibbering mouther is apparently scaring itself

d4 Bodytype/Movement (roll once when players first encounter it)

1. Levitation (as human)
2. Spider legs (as horse)
3. Membranous wings (as pterodactyl)
4. Immobile (attached to floor/wall, can teleport 100' each round)

d10 Noises That It Makes Continuously (roll at beginning of combat, and again when bloodied)

1. Spellcasting As If From 1000 Mouths
2. Song (it'll also dance a lil bit)
3. Religious Reading, Monotone
4. Children Laughing
5. Thunder and Rain
6. Mother Raccoon Devouring Her Babies
7. White Noise
8. Sex Noises/Someone Stirring Spaghetti
9. Whale Noises
10. Silence

d8 Attacks (roll once per turn)

1. Bludgeon (3d8)
2. Slashing x3 (1d8 each)
3. Shoot Teeth x5 (1d6 each, 100' range)
4. Bite (2d6 + swallow, 2d6 dmg/rnd in stomach, 8 dmg to cut out stomach)
5. Barf (30' cone, 6d6 acid damage, save for half)
6. Urticating Hairs (30' radius, 1d6 damage, save or scratch self for 1 dmg each turn, save ends)
7. Tongue Harpoon (2d8 and target is pulled adjacent, targets most distant PC, save vs disease)
8. Auto-Cannibalism (1d8 damage to self)

d20 Chaos Reigns (roll once per turn, after the attack)

1. Nothing.
2. Roll a new result on the Bodytype/Movement Table.
3. Split into two, each with 1/2 the original HP.
4. Reverse Gravity 50' radius (permanent until death)
5. Mirror Image (1d6 images) except they aren't illusions, but air-filled skins.
6. Barfs forth d1000 gp.  30' cone, 3d6 damage, save for half.
7. Miracle of Childbirth
1. 2d6 aggressive, pink goblins armed with organic spears, daggers.
2. Evil clone of a PC with weirdly organic copy of all equipment.  It's actually an evil midget version, so it  has half HP but is otherwise identical.  Clone and gear will melt into a bloody goo after 1d6 rounds, screaming curses and praising Cthulhu.
3. 2d6 hairless, legless wolves.  Use wolf stats except that they slither like snakes (half speed) and have -2 to AC.
4. Perfectly normal cow.  Terrified.
8. Turns invisible until next turn, teleports behind PCs
9. Baleful Polymorph on PC (turn them into sad flesh-blob thing that constantly weeps fog)
10. All wounded PCs begin gushing blood, which flows into the Psychoplasm.  Each PC not at full health takes 1d6 damage and the psychoplasm regains an equal amount.
11. Mass Hideous Laughter (save ends, pyschoplasm spends next turn laughing along with everyone)
12. Random PC gains temporary mutation.  Lasts 1d6 rounds.  Also, their eyes turn pink.
1. No head.  Blind, cannot speak.  Head appears on the psychoplasm for the duration and speaks (roll d4 on Noises table below).
2. No arms.  Arms appear on psychoplasm for the duration, which it uses to flip the bird.
3. Fire breath.  3d6, 15' cone.
4. Lobster claw arms.  Cannot hold sword, but can peeeench x2 for 1d6 each.
13. Vanishes into negaverse with PC.  Psychoplasm and PC get 1 round of combat atop an infinite, blood-soaked battleground paved with molars and broken crackpipes.  Both will return 1 round later.
14. Mutagen injection.  Heals a PC for 6d6 HP.  Then they must save or gain a mutation.
15. Mirror Skin.  Will reflect any spells that target it.  Lasts 1d6 turns.
16. Turns inside out.  Inside is somehow more disgusting than the outside. All witnesses must save or spend next turn vomiting.  Its AC is now 10+1d6. 
17. The next time it takes damage, it vomits blood, shrivels up like a scrotum, and plays dead for a turn.  (This is also what happens when it actually dies.)
18. Inhalation.  Like reverse dragon breath, 30' cone, save to avoid.  Those inhaled are swallowed (see Attacks table).
19. Doubles in size.  Double current HP.  This can only happen once (reroll otherwise).
20. Major Illusion.  Upper half of the dungeon is ripped away, exposing the stars of an alien sky.  Above, a vast thing that vaguely resembles a mosquito's face regards the combat dispassionately.  Cold wind blows through battleground, dealing 1d4 cold damage each round to those who failed their save vs. illusion.  Blood leaks from everyone's eyes.  Lasts until the end of combat. This can only happen once (reroll otherwise).