Pinotage said:
1) I've seen a whole host of characters posted here and on other ENWorld forums and a significant number of them contain more than one, often as many as 3 or 4, prestige classes tagged onto a base class. I know that's probably allowed, but how do you justify something like that? Do you allow characters to take multiple prestige classes? It just seems to be against the spirit of the whole concept, IMO.
It is a consequence of the attitude of 99% of the gamers (both players and DMs) towards prestige classes. Typically they use only what is printed on books, but since it doesn't perfectly "fit with the character concept"

they take a level here and a level there. Mostly however it's just because it's fun (not for everyone) to build a dread combination of abilities, although most people will
afterwards try to come up with a cover concept to justify it.
But doing both "perfectly" (the concept and the powerbuild) with existing material, despite the incredibly large amount around, is rarely possible.
The tragedy

is that it would be actually much easier to discuss all together at the game table (or at least the player and the DM) to write down ONE class variant or ONE new prestige class which fits the player's desire and the DM's need to keep troubles few.
Pinotage said:
2) I'm wondering how you justify having a huge number of high level characters and villians around.
...
Where do all those high level creatures your PCs face come from and how do you justify them being there?
I'm not good at running high-level games... When possible, it's probably fine to move the location somewhere else, or otherwise to make the high-level danger from somewhere else:
- from a distant land
- from the past (the ancient evil awakes...)
- locally, from a fast development (evil apprentice in the meantime has become big evil wizard)
For a while, you can just say the BBEGs has been secretly stirring in the background. The world doesn't have to be full of high-levels characters, maybe it's just full of characters
looking forward to become high-level, but not yet so.
When it doesn't seem to work locally anymore, have the party lured to a distant land, where legends speak of more dire perils (and rewards...).
It's a very cheap trick, but I still like the plane shift: characters discover planehopping and start adventuring into other worlds.
But of course, if one imagines the world full of 20lv characters just because the PHB has them, it's hard to explain why aren't they having a major effect on everyday life, and why haven't they basically taken over the world. If I have that feeling about my campaign one day, that it's becoming too full, it'll be time for a hard-reset
