How to Scale a "Player" Character to Be a Villain/Boss?

Question

I've been searching around, but I haven't been to find what I'm looking for via Google queries; but I presume that what I'm attempting would be pretty common.

Anyhow, are there any resources that would help me "convert"/"scale up" a character (created via the player character creation mechanisms) to be a villain or boss of some sort? Is there a simple heuristic where I can just plug in a few parameters and get some sort of output?

For instance if I have a party of X players and the party level is Y and I want the villain to be combat level Z, what should I do to meet those parameters? If concrete hypothetical numbers are helpful, let's say a party of size 5, a party level of 4, and I want the villain to be roughly equivalent to a combat level 6 creature.

If no official rules/guidance materials exist, I'm happy to hear of any techniques people have used to create villains with a character class.

Answer 1

There are rules for that

Page 72 of the Gamemastery Guide:

If you do choose to build an NPC fully using the PC rules, your NPC should generally end up being an appropriate challenge as a creature of their level. They will likely have lower statistics in some areas than if you had built them using the creature rules, but more options due to their full complement of feats and class features. This is best saved for important, recurring NPCs, especially if they’re meant to engage in social or exploration endeavors rather than just battles.

So if you make a PC sheet of a lvl 6 adventurer, it would be roughly equivalent to a 6th level monster: less raw power but more versatility.

I advise that you still quickly check that this "monster" has appropriate stats overall: for example if you optimize its build it could be stronger than it is supposed to be, and many PC classes simply don't work well as solo bosses because they can easily be cornered in a situation where they are steamrolled. You could quickly check that all the stats are within the standard ranges for monster creation, raise those that are below the "terrible" threshold, and lower those that are above the "extreme" threshold, so that they are not completely out of the charts.

Also, such monsters tend to take more time both to play and to build. Keep that in mind when you add one of these NPCs in your adventure.