This question is for the GMs out there. I am running a special, one-time adventure with nine PCs taking part! The most I have ever run at one time is seven (and that was in 2nd Edition D&D). Has anyone out there regularly run adventures with that many characters, and if so, how did you do it? Specifically, since challenge ratings are usually based on four PCs, how did you scale something with more than twice the PCs? Also, did you tend to build your encounters with a bunch of minion fodder to whittle down the party, or do you just beef up one or two baddies in each encounter?
I have used the fantastic adaptions of the Kingmaker AP for a six player party, but it just seems that it will reach the law of diminishing returns at some point. I have a feeling that ramping up the encounter strength by 125% will not end well for the party, or my sanity.
Please give actual examples that have worked in this situation, not “Try <blank> and it should work.”
Thanks in advance!
-Strange Doc
Edit: By the way, it will be first level. I know that definitely makes a difference.
Edit, Edit: I already have the plot, I just need the mechanics.