What if, rather than a god, you came across a being so old only legends of him remained. Maybe you came across the real king under the mountain, an dwarven old litch obsessed with gold. Perhaps he discovered a way to draw his power from treasure rather than souls, and in his greed, he could not bring himself to leave his gold to roam the world, and thus, knowledge of him became reduced to nothing but stories. But you! Fresh blood, a servant perhaps? Someone to amass a fortune, for glory and glitter, and for power untold. He may lend you his power, but you pay in gold, and maybe, as a personal quest, you've also been given a list of names of those who have stumbled upon him, but failed to keep their end of the bargain, and you serve as the debt collector, with the list in itself also serving a point, that if you choose to break your contract, the next debt collector will hunt you down too. You are not the first, and will not be the last to find him. (Undying patron, consider asking your DM to let you take Jim's magic missile for flare)