Greater Paraelemental of Magma

Second edition AD&D failed to make paraelementals for Dark Sun, so I will be creating some. I started with the lesser paraelementals and now it is time to introduce the greater paraelementals. Feedback is welcome.

"Burn everything! Magma for life!"

Stats after the jump.

Greater Magma Paraelemental
Climate/Terrain: Magma
Frequency: Very Rare
Organization: Solitary
Activity Cycle: Any
Diet: Any Solid
Intelligence: Average (8-10)
Treasure: Nil
Alignment: Neutral
No. Appearing: 1
Armor Class: 1
Movement: 10
Hit Dice: 10, 14, or 18
Thac0: 10 Hit Dice: 11
            14 Hit Dice: 7
            18 Hit Dice: 5
No. of Attacks: 1
Damage/Attacks: 4-40
Special Attack: Heat aura
Special Defense: See below
Magic Resistance: 50%/25%
Size: L (8'-16') 
Morale: 10 and 14 Hit Dice: Champion (15-16)
              18 Hit Dice: Fanatic (17-18)
XP Value: 10 Hit Dice: 3,000
                 14 Hit Dice:7,000
                 18 Hit Dice:11,000

Greater Magma Paraelemental
From the waist up, a greater magma paraelemental resembles a stocky humanoid being, but the lower portion of its body is nothing but an amorphous mass of molten stone. Most of its upper body is black rock, but a reddish heat shines from within – particularly from the eyes and mouth of the creature.
Greater magma paraelementals enjoy melting solid objects into liquid forms. They also derive a bit of sustenance from such actions.
Combat
When it comes to combat, the greater magma paraelemental uses its super-heated touch to inflict damage to a victim and sets combustibles (like wood) aflame. However, the greater paraelemental’s mere presence is also quite dangerous. Anyone within 30 feet of the creature is affected as if he were the target of an enhanced heat metal spell. That is, during the first round in the area, all metallic objects grow hot, inflicting 1d4 points of damage. During the second round, they inflict 2d4 points of damage to anyone in contact with them. In the third round (and all thereafter). anyone touching the scorching metal suffers 3d4 points of heat damage. What’s more, at this point, even victims who aren’t touching any metal sustain 1d6 points of damage from the incredible heat exuded by the monster.
Leaving the area reduces the effect by one step each round. For example, during the third round of close proximity to a greater magma paraelemental, an opponent in plate mail armor suffers 3d4 points of damage. If he leaves the affected area, he suffers only 2d4 points of damage in the next round. In the round after that, he suffers 1d4 points of damage. During the following round, his armor remains uncomfortably hot but inflicts no damage. And in the next round, the plate mail cools to its normal temperature.
Greater magma paraelementals can be struck only by +3 or better weapons, and they’re immune to the effects of heat and flame. They suffer normal damage from cold-based attacks.