Tier system

A campaign covers around 20 levels, and it usually takes 12 campaigns to reach legend level.

Tier-up Ability
This is a unique ability that the player defines. It should not be able to be found in any official books, and preferably not found on this site either. A character gains one at each tier-up beyond the first. Each tier-up should in general be more poweful than the previous. A tier 1 tier-up would be small potatoes compared to a tier 5 tier-up. Your tier 11 tier-up generally is a super-powerful ability that seems extremely overpowered. In general, if you plan on becoming a Legend (though the vast majority of people don't), your tier-ups should generally be focused around what your Legend will be. For example, Cyrus's tier-ups all focused around making his Wild Shape ability more powerful.

Tier 1
This is a normal 3.5 campaign with expanded classes relevant to the legends universe.

Tier 2
Add 10 to all stats.

At this tier a character gains their first tier-up. It can only have minor impacts, this is up to DM judgement. It is similar to a feat however depending on the difficulty of the campaign the DM may allow higher powered tier ups. The tier-up itself should generally be focused on improving some aspect of your class(es) that you don't like. For example, a rogue might allow for sneak attack to happen more often. A druid might increase damage dealt in Wild Shape by 1d8.

Tier 3
Double all stats.

Double your health total.

This tier-up should fix something about your character you don't like. A fighter isn't hitting enough? Give yourself an additional bonus to hit. A mage keeps loosing concentration on spells? Give yourself a bonus to concentration checks (or maybe make concentration checks based off of Intelligence rather than Constitution?).

Tier 4
Double all stats

This tier-up generally is similar to tier 2 or 3's ability. Fix or improve some aspect of your class you don't like.

Tier 5
Double all stats.

This tier-up generally is related to bringing something new to the table for your character. This tier-up generally won't have to do with your character's class, rather something tailored to your character themselves. Maybe your character loves talking to people, so you gain the ability to tell with 100% certainty when someone lies to you (though this is a bit under-powered for a tier 5 tier-up). Maybe your druid loves using wild shape so you expand it to include turning into objects. This tier really opens your freedom to create any ability you want.

Tier 6
Double all stats.

At this tier, the character starts to become more philosophy than a living being. Level up a second class simultaneously, choose one base attack bonus and saves, however gain all specials from all classes, including features such as spells and sneak attack. This tier-up is generally the same as tier 5. Get your character something nice to use.

Tier 7
Double all stats.

Double your health total.

For this tier-up, it generally is focused on breaking the game somehow. It is leaps and bounds more powerful than previous tiers, and shows that your character is now over halfway to legendhood. Your wizard not casting enough spells? Have spell points regenerate each round. Your fighter not doing enough critical hits? Make every 5th attack automatically be an unconfirmed crit.

Tier 8
Double all stats

Tier 9
Double all stats.

Tier 10
Double all stats.

Gain another class to simultaneously level up.

Tier 11
Double all stats.

Double health pool.

Tier 12 - Legend
Double all stats twice, i.e. quadruple all stats.

At this point, you are among the most powerful beings in the entire universe. Getting to this tier is infinitely more difficult than the previous tiers. See this page for a more in-depth description, as well as a list of all the legends.

Tier Exempt
This catagory contains a few exceptions to the tier system, and no being can reach this level, anything that exists here has been and always will be this level. For example, the True Immortals are considered tier 13. Other beings in this level include Tiers End, Adon , and others.