Power creep is a game phenomenon that involves the lack of balance of power between the old content and the new game. This phenomenon is often used by game developers to encourage players to take advantage of new things.
The new tanks in WoT are usually stronger once they are introduced and are undermined over time.
The Death Knight at WoW in the beginning was a figure powerful from the others.
Dark Lord in MU in the beginning was a figure deklasującą all the others.
Keep in mind that the phenomenon of power creep can have a very negative effect on the game if it is too strong. You will then see "The only right way" to achieve good results. Losing balance can also cause players to feel that the game is not fair.
Power creep can also occur by chance when game creators don't predict certain possible links between items in their production. For this reason, it is important to keep attentive documentation and describe possible threats and include them when adding new content to the game.