Koroth was responsible for cloning the original Kahless the Unforgettable, creating his rightful heir. He woke the clone before Worf in 2369 in an attempt to bring change to the Klingon Empire. In order to hide his ruse, Koroth pretended to doubt that the clone was the real Kahless. When the clone told the story of how the Klingon bat'leth was forged, a secret that was kept only with the High Clerics in order for them to verify Kahless's existence, Koroth declared him to be Kahless.
After a series of incidents that cast doubt that the clone was the real Kahless, Worf confronted Koroth and demanded the truth. Koroth admitted that he and the other clerics had used a sample of the original Kahless to create a clone, and had implanted memories so even the clone would believe he was Kahless. He believed that the empire was being destroyed by corruption and dishonor under the rule of Gowron, and Kahless would restore hope to the Klingon people. After Worf revealed the truth, Koroth compromised with Gowron for the clone Kahless to be made emperor. Although the position was just a figurehead, it would allow the clone to be the spiritual leader of the Klingons, while Gowron remained in charge of the government. (TNG: "Rightful Heir")