OK, so the BBEG wanted the artifact for his master. Is it possible for the PCs to intercept the BBEG before he gets to his master? What does it mean if the BBEG's master gets the artifact? Can they recover it from the BBEG's master? Sounds like another epic quest potentially in the offing...
I have only had 1 day to give it some thought, but I'm thinking they are just SoL.
*Spoiler alert for the Dead Gods adventure*
I won't bore everyone with the details, but the "master" is Orcus and he obtained the artifact (Wand of Orcus) as soon as the BBEG picked it up. I just didn't see any other way around that due to the flow of events.
This not only caused Orcus to regain his deity status, but he also now has complete control over a spell that can kill the gods. As far as dealing with Orcus goes, the PCs seem SoL.
For flavor, they'll now witness what allowing Orcus to return has done. Of course my first thought is to start having Cultists of Orcus popping up and the PCs can start dealing with them.
If anything, this failure will provide the game with a lot of interesting events. Probably more than what would have happened if they succeeded (so that's kinda cool). I'd like to somehow incorporate these new events into the adventures I have already been preparing that had nothing to do with Orcus (since I assumed they were going to succeed). I want this outcome to effect them in some way rather than it being something that happens in the background and is maybe heard about in passing. I'd like them to feel like their actions had a negative effect around the planes.
If anyone feels like throwing around some ideas, here are the scenarios I had planned to run before knowing the outcome to this adventure (can I somehow mix in some "Orcus" related events within these scenarios?)
1. A PC is given the chance to become a Dragonborn if the group successfully infiltrates a Yuan-ti fortress and kills a Green Dragon that has a lair below.
2. I'm reading Against the Giants and will be running it. Not sure yet what the hook will be, but maybe something that revolves around the Wood Elf Ranger PC.
3. The Wood Elf Ranger has a broken Orcusword and is trying to find the remaining pieces. I have a series of short adventures planned for this that is similar to the Rod of Seven Parts adventure.