Setebos has little else to do with his time but observe. As he surveys into the Tense River Basin, it is possible to draw his attention with a ritual. The repetition of a fiendish chant coupled with dancing before an open flame will call to him. But the offering of blood will bring him forth in the smoke of your pyre. For ten minutes you may attempt to make a deal with him. Deals may result in you gaining power, knowledge, or in very rare instances direct intercession. But the price for each is in alignment with the value. If no agreement can be reached by the end of 10 minutes, the opportunity is lost and Setebos will not respond to your ritual for one month. Dedicated followers of Setebos may also ask one question.
This ritual can be performed from a scroll by anyone regardless of class or level requirements. However such scrolls can only be crafted by Warlocks with Setebos as their patron.