Theorycrafting is the science of optimizing a character for a specific goal, such as optimizing a character for the traditional roles of tank, healer or DPS in a raid party. Frequently this is referred to as MinMaxing -- minimizing the bad attributes of a character while maximizing the good ones. MinMaxing is one of the most difficult, if not the most difficult challenges a player can take on and in the Elder Scrolls Online this challenge is compounded by the design of the four classes in the game.
Unlike most role playing games, the Elder Scrolls Online permits significant flexibility when building a character. There are ten races to be chosen from, each with their own Passive Abilities. The Skill Points of maximimum level character -- at the time of writing Veteran Rank 10 -- can be assigned to several many branched skill trees and are not constrained to a narrow set of abilities. Characters can wear any armor class -- Heavy, Medium and Light -- in any combination. They may be members of guilds, currently the Mages Guild and the Fighters Guild, which also improves specific attributes. Finally, characters can be bitten to become Vampires or Werewolves, which further modifies a character's attributes and abilities. The combinations of race, class, Skill Point assignment, armor, Guild membership and vampirism or lycanthropy creates a combinatory explosion that prevents any exhaustive search of the space of possible characters and how they might lead to the optimum for any chosen goal.
In addition to the challenge of evaluating a potential build for a specific goal, there are important circumstances when the goal itself can change. Ina Player versus Environment (PvE) settings, the purpose of a build is often unchanged for a long period of time. A specific raid boss in, for example, Craglorn will have the same game mechanics once released with very few changes. However in a Player versus Player (PvP) setting, the optimum build depends upon what builds other players chose. For example, if all players for some reason chose to be Dragonknight vampires, this might mean that a ranged DPS class would become a wiser build. In many games the optimum PvP builds may be found quickly and the theory for the best characters established. But in a game such the Elder Scrolls Online that permits such flexible character creation, it is possible that the optimum builds may be discovered slowly, changing the potential opponents that line up for battle in Cyrodiil. Given this, any PvP theorycrafting must take into consideration the state of the PvP when recommending a MinMax character.
Despite these challenges or perhaps because of them, theorycrafting is the Elder Scrolls Online may prove to more rewarding than in other role playing systems and there has been some early successes in this regard.