As mentioned briefly in several above sections, attacking is a critical role of monster cards. It is the primary means by which a player reduces the opponent's Life Points. The following describes standard battles under normal conditions, in which spells, traps, and monster effects are not taken into consideration.
During the Battle Phase of each turn, the player may choose to attack their opponent once with each monster in Attack Position (face-up in a vertical orientation), targeting one of the opponent's monsters or, if the opponent has no defending monsters, attacking them directly. When an attack is declared, the ATK points of the attacking monster is compared with the ATK or DEF points of the defending monster, depending on which position it is in. If both the attacking and defending monsters are in Attack Position, then the monster with the lowest ATK points is destroyed and sent to the Graveyard, with its owner losing Life Points based on the difference between the two monsters' ATK points. For example, if a monster with 1400 ATK destroys a monster with 1000 ATK, the owner of the losing monster will lose 400 Life Points. If both monsters have the same amount of ATK Points, both monsters are destroyed and neither player takes damage. Monsters with 0 ATK cannot destroy anything, that is to say, if two monsters with 0 ATK battle, neither monster will be destroyed.
When an attacking monster targets a monster in Defense Position (horizontal orientation), then the attacking monster's ATK points will be compared with the defending monster's DEF points. If the attacking monster has more ATK points than the defending monster's DEF points, the defending monster is destroyed, but its owner will not receive any damage to their Life Points (unless the attacking monster possesses a "Piercing Damage" effect, in which case the defending player takes damage based on the difference between the two values). On the other hand, if the player attacks a defending monster whose DEF points are greater than their attacking monster's ATK points, neither monster is destroyed but the attacking player will take damage based on the difference between the two values. For example, if a monster with 1000 ATK attacks a defending monster with 1400 DEF, the attacking player will lose 400 Life Points. If the attacking monster's ATK points and the defending monster's DEF points are the same, neither monster is destroyed and neither player takes damage. If a monster in face-down Defense Position is targeted for an attack, it is automatically Flip Summoned into face-up Defense Position. The card will then remain face-up until it is either destroyed or tributed, or allowed to be flipped face-down again by a card effect.
Direct Attacks can be performed when a player attacks an opponent who has no monsters on their side of the field (or utilises an effect that allows a direct attack even if the opposing player controls monsters). If the attack is successful, the defending player will receive damage to their Life Points equal to the ATK points of the attacking monster.