In World of Warcraft what is an overpowered class?

Answer 1

Classes (or sometimes specific talent specs) are considered to be overpowered (OP) when they have extremely high damage or survival when using the same gear as other, similar classes. This can mean that the class is extremely tough to kill in PvP battles by equal competitors, or that in raids a certain talent spec wildly outperforms others.

This is usually an exaggeration on part of other players, as you will find that in PvP an "overpowered" class usually only remains so as long as people haven't figured out how to counter their abilities, and in PvE such high damage might come at a very low survivability or a crippling dependency on perfect timing or mana management.

There are times when an ability or talent is considered to be more powerful than intended by Blizzard, in which case (hot)fixes are used to return these to more tolerable levels.

An example from the past is the Reckoning talent for Paladins, which could stack infinitely and then one-shot raid bosses (the so-called Reckoning Bomb). This was hotfixed within hours. Another example is Shadowpriest mana returns through Vampiric Embrace, which was changed from damage-dependent to a percentage of the target's mana. Recently, abilities once considered "mandatory" for raids, such as Bloodlust and Replenishment, have been spread among different classes so that these would see more use in raids, as well as making these abilities easier to access.

Overpoweredness, as an endnote, is also a matter of skill. A well-trained and experienced player can achieve things with a class that others cannot, which might lead to frustration among players. When this happens, and cries of outrage calls for rebalancing (or "nerfing") a class, this can also mean that less skilled players suddenly find their effectivity reduced.

Balancing an online game involving millions of players is a complicated matter, and examples of "overpowered" will continue to crop op regularly.