Today, almost every warrior in the Sphere has yellow, red, or purple crystals in their weapons that increase their power. But once upon a time, a long time ago, there were blue crystals. They were extremely rare and gave their owner's weapons magical properties.

Such stones were in Thrain's huge hammer. They allowed Thrain to forge the best swords, create toys, and resist Sark: the stones protected him from the man's ice rays. In addition, thanks to these stones, the hero was able to destroy Icecrown.

After Thrain's death, his hammer disappeared. Perhaps it is buried under the rubble of Sark's ice castle and is waiting for a new hero to get it.