I've skipped a lot of the posts in this thread since they centre on magic items.
As a DM who has played a LOT of campaigns with rotating DMs, the issue is this: The DMs have different play styles and when they clash it doesn't work.
Co-DMing can be a lot of fun, but its a lot of work. First, the DMs have to agree on the style for the campaign - this includes things like magic item acquisition, what happens to DM PCs when they DM, and most importantly the rules. If one runs the rules massivley differently than the other, this will not work! Second, the DMs have to regularly communicate storylines and plans to make a cohesive picture for the players - this can be used as a sort of troubleshooting technique before the event happens as the other DM can flag potential issues and they can be discussed. Third - The most important rule and I believe the DMG2 speaks about this - Never negate something someone else has created. If DM1 creates a city with powerful elves, DM2 should not destroy that city unless given permission by DM1. Always add to someone elses creation, never subtract.
I'm going to describe a bit about my current campaign to give you an idea of how successful co-DMing can be...
The campaign I currently co-DM introduced a mysterious villain whom they spoke with but never saw in the first adventure. They learned his name was Inajira and the PCs stole a mysterious artifact from him.
After speaking with the DM who was working on the next adventure, he wanted to tell a story where the PCs worked for a ruler that seemed benevolent and good but as things progressed it became obvious he was evil and would have to be taken down. This leader was introduced as Fenwiir Arijani.
Through our discussion we determined the villain that the PCs stole the item from (and who warned them they would see him again) was that leader of a nearby nation. The gist of the story was that the PCs town was threatened by a superior army and the PCs had to seek allies to protect their home. So it made sense to make allies of a nearby kingdom. They also had this powerful artifact that they needed researched since it was beyond their means. So, they went to the nearby kingdom and sought help.
Over the course of the campaign, they were required to help this leader consolidate his power by bringing others into his fold and killing bandits and such so that he had men to spare for their town. Now, on 16th level after the PCs have slowly been getting more and more warning signs that something is amiss, the PCs confronted him and discovered he is a Raksasha. Being that he was a Raksasha was bad enough. They had to take him down.
Now since we were co-DMing we were able to work on the story and give plenty of clues as to who Fenwiir was throughout the campaign but the PCs missed most of the double meanings until the end.
The payoff came during the battle to take down the Raksasha. Prior to the fight, we discussed a coat of arms that had the name of Arijani with an arrow pointing left just above his name. Halfway through the fight, one of the players recognized the signifigance of the arrow and read the name backwards which was Inajira. They then realized the stole the artifact from this guy and gave it right back to him and they have been his pawns ever since.
It was fantastic and these are the types of things that Co-DMing can pull off if done right!
As a DM who has played a LOT of campaigns with rotating DMs, the issue is this: The DMs have different play styles and when they clash it doesn't work.
Co-DMing can be a lot of fun, but its a lot of work. First, the DMs have to agree on the style for the campaign - this includes things like magic item acquisition, what happens to DM PCs when they DM, and most importantly the rules. If one runs the rules massivley differently than the other, this will not work! Second, the DMs have to regularly communicate storylines and plans to make a cohesive picture for the players - this can be used as a sort of troubleshooting technique before the event happens as the other DM can flag potential issues and they can be discussed. Third - The most important rule and I believe the DMG2 speaks about this - Never negate something someone else has created. If DM1 creates a city with powerful elves, DM2 should not destroy that city unless given permission by DM1. Always add to someone elses creation, never subtract.
I'm going to describe a bit about my current campaign to give you an idea of how successful co-DMing can be...
The campaign I currently co-DM introduced a mysterious villain whom they spoke with but never saw in the first adventure. They learned his name was Inajira and the PCs stole a mysterious artifact from him.
After speaking with the DM who was working on the next adventure, he wanted to tell a story where the PCs worked for a ruler that seemed benevolent and good but as things progressed it became obvious he was evil and would have to be taken down. This leader was introduced as Fenwiir Arijani.
Through our discussion we determined the villain that the PCs stole the item from (and who warned them they would see him again) was that leader of a nearby nation. The gist of the story was that the PCs town was threatened by a superior army and the PCs had to seek allies to protect their home. So it made sense to make allies of a nearby kingdom. They also had this powerful artifact that they needed researched since it was beyond their means. So, they went to the nearby kingdom and sought help.
Over the course of the campaign, they were required to help this leader consolidate his power by bringing others into his fold and killing bandits and such so that he had men to spare for their town. Now, on 16th level after the PCs have slowly been getting more and more warning signs that something is amiss, the PCs confronted him and discovered he is a Raksasha. Being that he was a Raksasha was bad enough. They had to take him down.
Now since we were co-DMing we were able to work on the story and give plenty of clues as to who Fenwiir was throughout the campaign but the PCs missed most of the double meanings until the end.
The payoff came during the battle to take down the Raksasha. Prior to the fight, we discussed a coat of arms that had the name of Arijani with an arrow pointing left just above his name. Halfway through the fight, one of the players recognized the signifigance of the arrow and read the name backwards which was Inajira. They then realized the stole the artifact from this guy and gave it right back to him and they have been his pawns ever since.
It was fantastic and these are the types of things that Co-DMing can pull off if done right!