Tier is a measure of a character's power, and the organizing structure for Character Levels. There are three Tiers in the game. A character will always be a member of only one tier, but they remain free to spend their Character Points on skills from their previous Tier.
Tier 1 is comprised of characters of Levels 1 through 9. In Tier 1, all characters are considered to be mortals.
Tier 2 is comprised of characers of Levels 10 through 19. When a character earns enough experience points to become 10th level, the character is presented with what may be the most important decision they must make: whether to Ascend and join the Heavenly choirs of Angels, Descend and cast their lot with the cursed hordes of Demons, or Transcend and remain human but become more than merely mortal. Whatever their decision they will then be able to join a Planar Guild.
Whether a character can Ascend, Descend, or Transcend depends upon their Morality. Only Evil characters may Descend to become Demons, while only Good characters may Ascend to become Angels. The option to Transcend is always available regardless of morality. Additionally, a character must have spent at least 70 Character Points on skills in order to enter a Tier 2 class -- the character's beginning skill counts as 10 Character Points towards the 70 point threshold.
Tier 3 is comprised of Character Levels 20 through 30. When a character gains their 20th level they are presented with another chance at choosing a class. Angelic characters can further specialize in angelic classes, demonic characters in demonic classes, and transcendent characters in transcendent classes. At this point Angels who have become Evil and Demons who have become Good are also given an option to switch sides and become Fallen and Redeemed, respectively.
A character must have spent at least 250 Character Points on skills or spells in order to enter a Tier 3 class. The free skill that they received when choosing a Tier 2 class does not count toward this total. A character must select a Tier 2 class before selecting a Tier 3 class.
Tier and Combat Experience
Depending on the Tier of the attacker and defender, the amount of experience earned from an attack can be modified. There is no experience modifier for attacking a character of the same Tier. Tier 1 characters will earn more experience for attacking Tier 2 characters, and even more experience for attacking Tier 3 characters. Tier 2 characters will earn more experience for attacking Tier 3 characters. Any character attacking a target of a lower Tier will earn less experience. Experience for Healing is modified the same way, and healers likewise receive more experience for healing characters of a higher tier and less for healing characters of a lower tier than themselves. Experience gain is modified by tier thusly:
Tiers one through three represent the power attainable by player characters, but the lore of Nexus Clash contains beings of greater power whose capabilities can also be measured by Tier. Just as a level 30 Lightspeaker is greater than a newly Ascended level 10 Shepherd, higher tiers represent an exponentially greater level of power than what player characters can achieve. However, the history of the Nexus is filled with tales of how player characters working together have aided or toppled such beings, and the power to determine the outcome of Breaths rests in the hands of player characters alone.
Tier 4 characters are beings that have, through acquisition of great power, risen beyond the cycle of eternal death and rebirth in which player characters are trapped. Many Nexal pilgrims and scholars have sought this state, being understandably weary of unending war and pain, but with escape from the cycle comes great risk, for those who cast themselves out of the Nexal cycle - or are pulled out of it by a higher power - are no longer able to Respawn and stand at risk of permanent death without the direct patronage of an Elder Power. Examples of Tier 4 characters include the founders of various Classes such as Haldos (the first Lich) and Maeval (the first Revenant), as well as powerful forces of nature such as the three Great Dragons that once roamed the planes.
It is unclear how many Tier 4 characters exist. All of the Elder Powers count at least one such entity among their followers, and some have many more than one. Tlacolotl in particular is fond of "rewarding" demons with "promotion" to this rank, who then find themselves utterly enslaved by him lest they fail him and perish forever - which they inevitably eventually will, given the impossibility of one's life being truly valued by Tlacolotl. Some other Powers are far kinder to their greatest tools, but such beings are still inexorably bound to the goals of their patrons. An unknown number of Tier 4 characters exist who are "free agents" beholden to no one, but with no one to help them should they fall.
Tier 5 characters are avatars or masks created by the Elder Powers to interact more directly with mortals. The terms of the Struggle for the right to shape the next world forbid direct intervention with the Powers' divine abilities, so avatars were created - initially by Marquai and Tlacolotl as a workaround to game the system. Other Powers protested, but eventually each of them, seeing the advantages, created avatars of their own such that each Power has exactly one. In time, the universal adoption of avatars dulled the advantages of having one, but not the costs, so they are now rarely seen. They are powered and sustained by mortals' adherence to the ideals of each of their creators, and as such have come to share many of the limitations of the Powers.
Tier 6 would, theoretically, represent the Elder Powers themselves.