Find Thrain's hammer!

Today, in the Sphere, almost every warrior has yellow, red or purple crystals in his weapon, increasing his power. But once upon a time, a very long time ago, there were blue crystals. They were extremely rare and endowed the owner's weapon with magical properties.
 
Such stones stood at Train in his huge hammer. It was they who allowed Train to forge the best swords, create toys and resist the Sark: the stones protected him from the icy rays of man. In addition, thanks to these stones, the hero managed to destroy the Ice Crown.
 
After Thrain's death, his hammer disappeared. Perhaps he is buried under the rubble of the ice castle of Sark and is waiting for a new hero to get him.