A volcano of Klingon legend into whose lava Kahless plunged a lock of his hair, which he then shaped into the first bat'leth.
The Kri'stak Volcano is a place in Klingon legend, described in the Next Generation episode Rightful Heir.
According to the story, Kahless climbed the volcano, cut off a lock of his hair and thrust it into the molten rock. He cooled the burning hair in the Lake of Lursor and twisted it into a curved blade, the first bat'leth, with which he killed the tyrant Molor.
The tale was kept secret by the high clerics so that it could be used to test anyone claiming to be the returned Kahless. When the Kahless who appears on Boreth in 2369 tells it correctly, Gowron's doubts are shaken, until it emerges that the clerics had taught it to their clone.