Pathfinder Adventurer's Guild
Tier 4 is where Pathfinder starts to leave the realm of its greatest inspiration (Tolkien-esque fantasy) and starts to mimic more powerful characters. Powerful superheroes, anime ninjas, regenerating time-travelers, and the like are the peers of characters in this tier. Some established RPG settings would have your character be the most powerful mortals in the realm if they reached this level. At this point, you are likely as well known as the most famous people in history (just don’t forget how many of them were murdered). As far as the guild is concerned, you’re probably running things (if that’s your interest) or at least dictating the terms of your assistance.
Tier 4 spans from level 12-16. At this point death by mook is almost impossible while death by a single spell or strike from a power level peer could likely cripple you if not kill you outright. The Martial/Magic curve is almost completely in favor of the spellcasters with the exception of a few expertly crafted martial builds.
Adventures here can start to incorporate everything and anything. Waging wars on behalf of the forces of good, invading other planes, uncovering artifacts believed lost to time and dealing with all but the most big of the baddies are all expected.
Examples of characters in this tier: Iron Man, Spider-Man, Dumbledore, Hercules, Dr. Who, Sauron.