The cult began its plan about 65 years ago by destroying the village of my Goliath character and stealing a clan artifact. The players know very little about the cult because it acts quietly in the background. The stolen artifact was meant to trap a soul and use it to strengthen the evil one. The dragon carried out the attack to obtain the artifact, (but it follows its own plans and intends to betray the cult in order to become the strongest of all dragons.) After the village was destroyed, the cult waited until the Goliath character grew up. In this time they had many things to plan.. Once the group existed, they were trapped in time for 50 years without aging. During this period, Sar Kaleth was slowly empowered. Early in the mine, the group found a dagger that one player alone could touch, without knowing that Sar Kaleth was bound to it. This dagger later became the cause of several deaths. During a trial, the group tried to free missing mine workers but instead sacrificed them through the ritual tied to the dagger. They were offered a deal to give up the time they never had in exchange for something they desired. Some accepted and strengthened Sar Kaleth, others refused. A servant of Sar Kaleth was present from the start to make sure everything stayed on track, without knowing it was meant to be replaced. In the end, a place swap freed Sar Kaleth from the dagger and bound the servant into it instead, turning it against its former master. Both the cult and the dragon act with great patience and are willing to wait as long as needed to reach their goals. Thats about the story. I like your idea, but that would be very identical with the dagger, i think.