Wheeee!
From D&D Companions Set:
Hydrax*
Armor Class: 2
Hit Dice: 5** to 12**
Move: 60’ (20’)
Swimming: 180‘ (60‘)
Attacks: 2 claws or special
Damage: 1-10/1-10 or see below
No. Appearing: 1 (1)
Save As: Fighter, double level
Morale: 9
Treasure Type: Special
Alignment: Lawful
XP Value by Hit Dice: Variable
A hydrax is an intelligent crab-like creature made of ice. It is native to the Elemental Plane of Water, and almost never found on the Prime Plane. Although the hydrax are Lawful in behavior, most are evil.
A hydrax has 6 legs and 3 claws, equally positioned around a crab-like body. Hydrax are immune to normal weapons, all 1st and 2nd level spells, and to all attacks based on fire. A hydrax can detect invisible at will, and can cast detect magic, web, dispel magic, ice storm/wall, and water to ice 3 times per day (all as if a 9th level magic-user).
The hydrax use tools made of ice, and build cities and devices of all sorts. Their enemies are the undines and the kryst, and they fear air-type creatures and attacks.
From Mystara Monstrous Compendium Appendix:
The elementals of law are intelligent creatures native to one of the four elemental planes. Each dedicates itself to maintaining the forces of law on both its home plane and the Prime Material Plane, yet they differ wildly in their methods of achieving this goal.
All elementals of law are immune to poison, normal weapons, and 1st- and 2nd-level spells. They also can cast detect invisibility at will.
Hydrax
Climate/Terrain: Any water
Freq: Very rare
Org: Solitary
Activity Cycle: Any
Diet: Ice
Int: Very (12)
Treasure: Nil
Alignment: Lawful evil or lawful neutral
# App: 1
AC: 2
Movement: 6, Sw 18
HD: 5-12
THAC0: 5-6 HD: 15, 7-8 HD: 13; 9-10 HD: 11, 11-12 HD: 9
# Attacks: 2
Dmg/Att; 1d10/1d10 (claws)
SA: Spells
SD: See Below
MR: Nil
Size: L (8' wide)
Morale: Elite (14)
XP Value: varies
Hydraxes are native to the Elemental Plane of Water, and of the elementals of law, they seem the least likely to venture from their home plane. These large, crablike creatures of deep blue ice have 8-foot bodies with six legs and two claws.
Combat: In battle, the hydrax attacks with either its two icy claws (causing Id10 points of damage each) or with spells. It can cast detect magic, web, dispel magic, wall of ice, and transmute dust to water three times per day. Once per week it also may use reflecting pool at the level at which it casts the others-as a 9th-level spellcaster. Hydraxes are immune to all water-based attacks, but suffer maximum damage from fire-based attacks.
Habitat/Society: Hydraxes are solitary creatures who, though lawful in behavior, tend to align with the forces of evil. They spend much of their time creating complex cities and devices of great beauty with tools made of ice. They seldom work together on such efforts, however. Each hydrax instead waits its turn to add to their strange group efforts.
Ecology: The most common enemies of the hydraxes are the undlnes and the erdeens; the crablike elementals fear earth-type creatures and earth attacks, pamcularly those of the erdeens.
