Hi there!
So it looks like I am FINALLY going to get a chance to GM a Pathfinder campaign. This will be my first time, and I had a couple questions, one simple and one not-so-simple, I was hoping some more experienced GMs and players might be able to chime in on.
1) I’m trying to get a sense of how to calculate the CR of a group battle. If it’s multiple creatures with the same CR, you add numbers based on the chart on page 398 of the CRB. So if it’s 4 creatures with CR 16, you add 4 to the 16 and it becomes a CR 20. So far, so good. But what do you do if the encounter has mixed CRs? Let’s say it’s 4 monsters but one is CR 16, two are CR 12, and one is CR 5. My best guess was that you’d average the CRs and add 4, but that would make the hypothetical scenario above a CR 11.25, which sounds low. Is there a rule for this I haven't noticed? I looked through the CRB and the bestiary appendices and didn't see anything.
2) Despite my best efforts, I only got one friend to agree to play the campaign with me. We decided we’d give the solo campaign concept a shot. One possibility we discussed was having me run some party NPCs to balance encounters, but I’m wondering if that would take the focus away from my friend’s PC, which I’d like to avoid. I want his PC to be the hero of the story, or at the very least the leader of the party. Other than stocking him up with magic items for healing/enhancements, are there any ways I might be able to tailor the encounters to fit one character? Is this at all feasible from a balance perspective? I am not certain but it is most likely he’ll be playing a martial class, like fighter, inquisitor, or brawler.
Any thoughts you might have for questions 1 and/or 2 would be greatly appreciated :)