The party knew that there was no way that Mammon would sign any contract which would prevent him from sending his agents into the mortal realm, but they knew that there was someone in Mammon’s Hell who was actively working against him. They also knew, and I’m pretty sure it’s because Mammon told them, but I could be wrong, that destroying the sword Mammon had created for Raziel decreased Mammon’s power. It doesn’t make a whole lot of sense, if you think too hard about it, but it helps if you think of artifacts Mammon creates as being extensions of his own power: not only do they contain a piece of his power, but, when destroyed, it severs the link between himself and the item the same way that severing a limb would cause you to lose the blood in both the limb and in the rest of your body. And if I can explain magical artifacts using an analogy where you get chopped into pieces, then I’ve had a good day.
So they fell back upon the strategy used by all true heroes in times of need: they hit the library and researched! Cheryl quickly learned of several other important artifacts of Mammon that the party could seek out and destroy: one a statue of Mammon owned by a wealthy merchant named Salem Zayne in Faranoth, and a golden scimitar said to have been delivered by a god of gold to a South Mexican city.
Well, our heroes didn’t take long to find Salem Zayne, but it turned out that his statue was just kind of cool, and not actually magical. The guy was a collector, though, and Artemis smoothly lied to him and said that he represented a buyer from Angler Enterprises who was interested in purchasing some of the man’s collection. He did tell them of another man, one Chandler Barclay, who Zayne thought might possess an item with an affiliation with Mammon. That’s about as far as that went, and the merchant’s name was forgotten just a few minutes after the party left.
Then the party headed off to the remote village, where they confronted the old priest. Some interrogation—and some failed attempts on the priest’s part to use his amulet—later, they figured out that the amulet was given to the priest by Mammon some time ago. It had the power to force people to give their wealth to the amulet’s wearer, but, unfortunately for the priest, the DC 25 Will save just wasn’t high enough to get a single one of the party to give up their cash.
They took the amulet, looted the old man’s home of all his ill-gotten riches, and headed back to Vardiss’s manor with the money. Presumably, that money originally belonged to the other people of the man’s town, but who cares about them?
With Thomas and Balrorn wringing their hands nervously and providing careful instructions, the party destroyed the amulet. Artemis held it in his hands while it was destroyed, which forced the power of Mammon into him and transformed him into a half-fiend. That was his plan, though, so he was happy about it.
And so, with another party member forever warped by the powers of magic and extraplanar Lords, the party headed off to Mexico to steal a golden scimitar.