6 player adjustment advice

[Gibo Auja]

So I'm about to kick of this AP two weeks from now. As the character builds come in, I'm starting to get worried about the challenge.

As I understand adding another 2 CR to the encounter is technically what I'm supposed to do, but I just don't know if that's going to cut it. Currently the players classes are
-Bard dawnflower dervish
-investigator mastermind
-kineticist blood
-Alchemist Tinker
-Rogue deadly courtesan
-????

If anyone has run the first book are they just going to run rough shot over it?

I didn't want to, but I could start redesigning a lot of the encounters, add 2 cr or 3 cr creatures. Advance a couple of npcs.

Any advice or tips on adding a bit of difficulty to this ap I'm not to concerned about running a difficult campaign. I just don't want them to walk through everything.

[Trichotome]

It's hard to say without a full idea of your players and how they play, but generally I think you're better off not bumping up the challenge of the first book much since players are still too early in their builds to steamroll things that easily, even with the extra players (and based on those archetypes at least a couple of them are going to be combat-light). I had a GM who amped up all the stats of all his creatures in book 1 and none of us could get past their ACs, making the fact that there were six of us largely irrelevant (and that's accounting for aid another). For my own 6 player run of Hell's Rebels I've found maxing out hp does the trick just fine to keep enemies alive for more than a round without making things unfair for the players, at least during the early levels. With this AP specifically, I'm not seeing anything in particular that would suggest needing to adjust the difficulty much beyond that so far.

I'd suggest trying max hp with part 2 of the first book and see how it goes, and then adjust part 3 based on how they performed during the last part and so on and so forth. You can always build alternate versions of the lesser guys of part 3 in advance so that you can just switch which statblock you're using on the fly. That's what I've done previously and it works quite well.

Fortunately, because this AP is so heavily skills and intrigue-based, you won't need to modify nearly that many encounters, since skill checks don't exactly become easier the more players there are. Though for any event that has a set number of rounds and a limited number of actions, you might want to either decrease the amount of rounds or increase the amount of content, since that can actually have a significant impact on the game's progression.

[Ring_of_Gyges]

In theory +1 CR should cover 6 players. +2 CR is meant to be a doubling of threat.

That said, the CR system is pretty inexact. PCs of nominally equal level can vary quite a lot in power level based how well they're built and played. Do as much modification as you're willing to, but I've generally found APs underestimate what PCs are capable of and most fights need powering up a bit.

Just keep in mind erring on the side of a fight being too easy lets the story advance, erring on the side of a fight being too hard risks a TPK that derails the game. It's not the end of the world if the PCs win every fight, in fact most APs pretty much require them to do so in order to function.

[The Rising Phoenix]

I covered this topic briefly in one of my earlier notes after my first play through.

For Part 1, I decreased most of the social round duration by 1 round to accommodate for a 50% larger party. In addition, I added additional NPC's to allow them more targets to direct their influence. I also added a few more sycophants to the Trant encounter.

For Part 2, I adjusted several (but not all) of the combat encounters by adding additional creatures or adding an advanced template. For example, instead of 2 Walcofindes there were 3.