In a battle between two Attack Position monsters:
- If one ATK value is lower than the other, the one with the lowest ATK is destroyed. The owner of the destroyed monster takes damage equal to the difference between the two ATK values, unless a card effect prevents Battle Damage.
- If both ATK values are the same, both monsters are destroyed (called a Double KO), and no damage to Life Points is inflicted on either player, unless a card effect dictates otherwise. The only exception to this would be when both monsters have 0 ATK, in which case neither monster is destroyed.
When attacking a Defense Position monster:
- If both the ATK value of the attacking monster and the DEF value of the attacked one are the same, neither monster is destroyed, and neither player loses Life Points.
- If the ATK value of the attacking monster is higher than the DEF value of the attacked one, the Defense Position monster is destroyed, and no Battle Damage is taken, unless the attacking player has a piercing effect that deals the difference between the ATK and DEF values as Battle Damage.
- If the ATK value of the attacking monster is lower than the DEF value of the attacked one, the difference between the ATK and DEF values are dealt as Battle Damage to the attacking player and neither monster is destroyed.
If the opponent has no monsters on the field, damage is dealt to the opponent's Life Points equal to the total ATK value, if the attack is not blocked or disrupted. This is called a direct attack.