It has been stated that a characteristic mark of a combination is surprise; surprise for the defender, not for the assailant, since otherwise the combination will probably be unsound.
Eugene Znosko-BorovskyAll chess players know what a combination is. Whether one makes it oneself, or is its victim, or reads of it, it stands out from the rest of the game and stirs one's admiration.
Eugene Znosko-Borovsky