When Superman and Lois Lane traveled back in time to Krypton (or so they believed) they were persucuted by General Zod who wanted to keep Krypton clean of alien impurities. Zod send his best hunters, Kru-El and Faora after the trail of the visitors. They catch them in the Proto-tombs of Xan, where they almost captured and killed the pair. Only the intervention of the Xan themselves saved the earth couple.

In their next encounter with Superman, the hounds had allied themselves with the science council, now leaded by Jor-El, against the religious cult of Rao. Under the promise of recive the cloning technology developted by Jor-El, the hunds wanted to resurrect their leader, Zod and bring a new order to Krypton. Depiste their intentions both died heroically fighting against the acolytes of Xon-Ur.