Direct attack

From Yu-Gi-Oh!

A Direct Attack is the process where a Monster's whole ATK value is subtracted from the opponent's Life Points, either when there are no Monsters on your opponent's side of the field, or if the attacking monster has the ability to attack directly, either by its own effect or the effect of another card. The damage inflicted as a result is known as "Direct Damage". There is almost always a risk in a direct attack as the opponent frequently has a spell or trap card set as a counter.

Many monsters have the ability to perform a Direct Attack even when there is a monster on the opponent's side of the field--however, for balancing, they typically have very low ATK values or an added disadvantageous effect (for example, Crystal Beast Amethyst Cat has a Special Ability that allows you to halve that card's ATK to allow it to attack your opponent directly) Others ways to attack directly includes special spell cards that allow this effect. Usually it's after you attack a monster and destroy it successfully.