I'm running the Pathfinder 2e Abomination Vaults adventure for a group of 5 players, though I've set it in my own homebrew setting and have not shied away from deviating from the published adventure. I'll try not to, but I may let slip some minor AV spoilers
The players have just reached the end of book 1, and are about to go into book 2. At this point, about a month of in-game time has passed since the adventure began, and one week into the adventure there was a big supernatural event which made big news around the town that the adventure is set in. I like to play up the verisimilitude of the setting by having NPCs and the world react to the things that happen, as well as to the passage of time.
One thing I've come up with which I'm excited to see play out is that enough time has passed that word has spread around the local area about this megadungeon that has been discovered near the town. The players have been telling everyone who will listen about this heretofore undiscovered complex. In my mind, this would mean that other parties of adventurers would come to the town with the intent of doing the same thing the players are doing: looting dungeon, killing baddies, leveling up, getting rich and famous.
I've created a rival party of five adventurers of the same level as the players. This rival party is called "The Vanguard Edge" (or simply "The Edge"). I've spent a chunk of the last few days making notes on how to RP and employ The Edge. Here's what I've got so far:
The party is likely to try to join forces with The Vanguard Edge. This should never be possible.
The Edge don't follow the same rules as other NPCs. Think of them as a group of DM-controlled player characters. They know the rules of adventuring and they think like players.
The Edge are not villains. They are fundamentally "good guys", but their goal is to eat the party's lunch. They want to go into the Abomination Vaults and find all the cool loot first
In general, the Edge fulfill the negative stereotypes that most people have of adventurers. They are demanding, dismissive, and arrogant. They flaunt their wealth and brag about their exploits, they get bored when they go too long without fighting something. They sometimes speak in slightly more metagame terms, such as talking about their hopes to "level up" and "gain experience".
If the party ever shares useful information with The Edge, they will look at it with some skepticism. The members of the Edge would never dream of sharing Intel with other adventurers.
The Edge will occasionally have reached certain places first. This should be used sparingly, and only when it is a real gut punch for the party. It should be easy to tell where they have been, because they are completely unsubtle in their approach to adventuring.
Sometimes the implication of treasure can be added to the adventure, but with the added implication that the Edge got to it first. Maybe Abomination Vaults doesn't explicitly mention treasure in some room, but there was some in there, and the Edge already took it.
If an encounter is about to turn into a TPK, the Edge can show up to save the PCs. But they will never let them live it down.
Those are the notes I've made so far on how to use this new element of my campaign. I'm curious if anyone out there has any thoughts, either in things I've noted or things I've missed. I'd love folks to give their feedback
First, don't use player stat blocks for enemies. They aren't balanced like enemies. At best you'll be obviously pulling punches, at worst they'll cream the players.
Second, what's your goal here? Are these guys the main villain in your story, sort of an Ash vs. Gary rivalry? I feel like it's going to take the wind out of your players' sails to have the good stuff looted before they even get there.
First, don't use player stat blocks for enemies. They aren't balanced like enemies. At best you'll be obviously pulling punches, at worst they'll cream the players.
That would be true if I were 1. Intending for this to turn into a fight, and 2. Playing 5e. The Pathfinder GM guide literally recommends that you can just use the PC creation rules for creating NPCs that have PC classes. And the intent here is that they don't fight. If they do, I fully intend to obviously be pulling punches. I don't want the party to think this is a problem they can kill their way through.
Second, what's your goal here? Are these guys the main villain in your story, sort of an Ash vs. Gary rivalry?
The main goal is to create a new source of pressure. The party have begun developing a habit of going into the dungeon, doing one fight, and then going back to town and resting until the next day. This will make it so they begin feeling a bit more pressure to stretch out the adventuring day, since they want to give the rivals less chance to go in between their trips.
Also yes, the intended dynamic here is like Ash and Gary. Notably, Gary was not the villain, Team Rocket was. These rivals are dicks, but they aren't evil. As I said in the notes, they are "the good guys" and want the same thing as the PCs, but adventuring is a zero sum game.
The other hope is that it makes the world feel more dynamic and responsive. Like it's a living world and not a video game world where all NPCs exist only to talk to or be killed by the PCs.
I feel like it's going to take the wind out of your players' sails to have the good stuff looted before they even get there.
My goal is to have it feel like the PCs have to be worried about losing out on some cool loot, but without actually removing from them much of the treasure they would normally be entitled to per the game balance. That's why I mentioned I would add in the implication of even more treasure than the adventure provides, but with the added implication that the rivals already took it. So that the adventure stays balanced but the party feels like they missed out.