Stygian Ice

This extraplanar ice comes from Stygia, the fifth layer of Hell. Infused with the soulless evil of that realm, along with the magical waters of the river Styx, stygian ice is black and constantly crawls with a thin layer of pale blue mist. Stygian ice is much colder than normal ice, and it melts slowly in nonfreezing environs. The coldness that this ice exudes is magical in nature, and freezes the mind much more rapidly than flesh.
Stygian ice deals 1d6 points of cold damage per round of contact. Worse, if a creature takes damage from this supernatural cold, it must make a DC 12 Will saving throw or take 2 points of Wisdom damage as its memories are slowly frozen. If a creature’s Wisdom is reduced to 0, further contact causes Constitution damage. A creature whose Constitution is reduced to 0 by Stygian ice rises as a wraith in 2d4 rounds.
Stygian ice is not much harder than normal ice, so it doesn’t make effective armor. Weapons made of Stygian ice are somewhat fragile, and each time they deal damage the wielder must make a DC 15 Reflex save to avoid dealing the same amount of damage on the weapon itself. Stygian ice weapons deal 1d6 points of additional cold damage on a hit; if the creature hit takes cold damage, it must make a DC 12 Will saving throw or take 2 points of Wisdom damage (or Constitution damage, if Wisdom is at 0). This damage applies to the wielder of the weapon as well; a character who wishes to wield a weapon made of Stygian ice is advised to seek out protection from cold damage.
Stygian ice has 5 hit points per inch of thickness and hardness 3. Magical fire damage is not halved when applied to stygian ice. An object made of Stygian ice takes 1 point of damage per hour it exists in an environment above 40° F; this damage overcomes the ice’s hardness. As it melts, the ice gives off foul vapors that nauseate anyone within 5 feet who fails a DC 12 Fortitude saving throw.

Source: Frostburn

Type of Stygian Ice Item	Item Cost Modifier
Weapon	+6,000 gp
Other objects	+2,000 gp/lb.