Although I write products for the Pathfinder RPG on the assumption that people are using the standard rules, I almost never use the standard rules in the campaigns I run. I'm constantly tinkering with variant rules and inflicting them on my players. Mostly, that's good; I like ramping up the power of the enemies and the characters both. For example, in the Shattered Star adventure path I'm running, I'm using allowing my players to use some lightly modified gestalt rules--each character gets the benefits of two classes at once. I've got a cleric/zen archer, a wizard/magus, a fighter/alchemist, a fighter/monk, and a bard/oracle. Everyone seems to be enjoying it. So much so, in fact, that some of my players have asked what I plan to run next. (Currently, they're about a third of the way through chapter 5 of 6, so about 75% done with the whole campaign; playing every other week, I expect to be done sometime this summer.)

I don't know that I want to have gestalt PCs again; that seems to have been a success both times I've offered it, so I'm ready to try something else.

Flash back to some righteous indignation from 2007. At that time, Wizards of the Coast was producing some preprinted map packs that had a few simple encounters included with each. One of these map packs--City of Peril--was for slightly higher-level characters. It was pretty clear to me that the writer didn't know the rules well; one of the opponents was a "human shadowdancer 12" and another was a "human assassin 12." Wait a minute. Those are prestige classes; you have to be something else (usually a rogue, for those particular prestige classes) before you can take levels in the prestige class. "Human rogue 7/shadowdancer 5" would be correct. "Human shadowdancer 12" was not. At first, I was pretty indignant that the company responsible for the rules would release such obvious errors, and I remember being altogether too irritated by it at the time. But something in that idea stuck: why can't you take a prestige class right at 1st level, without any other classes? What happens if you just ignore the prerequisites entirely? Wouldn't you be the most quintessential shadowdancer around if you didn't muddle your advancement with time as a rogue? That seemed kind of neat.

I never did anything about it, but I think I'm going to. I plan to run my next campaign with the following rule: you must pick a single prestige class and take all your levels in that prestige class. Ignore the prerequisites. If the prestige class obviously intends for you to have some weapon or armor proficiency before entry--like the stalwart defender does--you get those automatically at your first prestige class level. 

So this seems obviously overpowered: assassins are doling out death attacks at first level, and utterly eliminating opponents by 10th level. Shadowdancers are teleporting around the battlefield at 4th level. Mystic theurges get piles of spells right out of the gate. It'll be madness.

And it'll be awesome.