Upon reaching 6th level, characters cease normal advancement. Instead, for each 5,000 additional
experience points beyond 6th level the character may select a new feat that they meet the prerequisites for. The list of feats available for this “epic advancement” is expanded to include both epic and signature feats that are unavailable to characters who are “merely” 1st to 6th level. These feats are designed so that a character can approximate being 7th level after five epic advancement feats, and even have the opportunity to earn a power or ability that would typically have been earned at 8th level (or 9th in the case of sorcerous bloodline powers).
The fundamental rule should have a great impact on world design – spells for PCs and NPCs stop at 3rd level except for a few rituals, extremely powerful monsters are exceptionally rare if not absent, and magic items are vastly limited.
One way of envisioning the character levels is that a 1st level character is roughly equivalent to a journeyman craftsman – a squire just completing their training, a conscripted farmer just off their first tour of duty, or a wizard just finishing their apprenticeship. A 3rd level character is roughly equivalent to a master craftsman – well above the peasants, common laborers, and even craftsmen in most rural villages, but not uncommon in the towns and cities. Fifth level would include the renowned master craftsman – one who has achieved a rare height for their profession; they would only be found haphazardly in anything smaller than a city and be few in number for any given profession even in a larger city. Beyond 6th level, a character or NPC would be truly epic, the type about whom legends will be spun unless they work hard to hush them up.