Paraelemental of Silt

Second edition AD&D failed to make paraelementals for Dark Sun, so I will be creating some. I've decided to start with the lesser paraelementals and eventually get to the greater paraelementals.
I've posted all of the lesser paraelementals, so now I'm moving on to the full paraelementals. Feedback is welcome.

Dust and sand ripping flesh from your bones.

Stats after the jump.



Silt Paraelemental

Climate/Terrain: Any Silt
Frequency: Very Rare
Organization: Solitary
Activity Cycle: Any
Diet: Silt
Intelligence: Low to High (5-14)
Treasure: Nil
Alignment: Neutral
No. Appearing: 1
Armor Class: 2
Movement: 21
Hit Dice: 8, 12, or 16
Thac0: 8 Hit Dice: 13
            12 Hit Dice: 9
            16 Hit Dice: 5
No. of Attacks: 1
Damage/Attacks: 7-28
Special Attack: See Below
Special Defense: +2 or better weapon to hit
Magic Resistance: Nil
Size: L-H (8'-16') Height = HD
Morale:Champion (15-16)
XP Value: 8 Hit Dice: 2,000
                 12 Hit Dice: 6,000
                 16 Hit Dice: 10,000

Silt Paraelemental
The silt paraelemental appears as a vaguely humanoid shape formed entirely out of silt. It has no features and seems to enjoy others reactions to its alien appearance. It has no legs, but rather rolls on a body of loose silt.
Combat: The silt paraelemental can travel freely through silt and loose sand. When fighting, a silt paraelemental can lash out with a pseudopod of swirling silt. If the paraelemental makes an unmodified (natural) attack roll of 19 or 20, it completely engulfs its opponent. Engulfed victims are powerless to act and their flesh starts being ripped from their bones. Victims suffer 2d6 points of damage per round until they die, at which point their bodies are nothing but bones or chitin. A paraelemental can engulf only one creature of size S or M at a time. Once a victim is engulfed, the victim must make a strength check with a -4 penalty to break free.
The monster can transform its body into a raging silt storm with a radius of 40 feet. Those caught within the storm must make a successful saving throw versus rod/staff/wand or become blinded for 1d10 rounds. However, nothing can save them from the storm’s physical battering, which causes 1d2 points of damage per Hit Die of the paraelemental.