Event (イベント Ibento) is one of the card types in Z/X -Zillions of enemy X- TCG. As the name suggest, they represent various "event" that happen in the story of the game. Event Extra cards are also treated as Event during gameplay.
Event cards are single-use cards with various effect that able to affect the gameplay (e.g. deal damage to Z/X, draw cards, increases Power, etc.) and act as either support or hindrance for both Z/X and Player. Together with Event Extra, they are also the only cards with the Event Ability (イベント能力 Ibento Nōryoku), which is performed when they are played.
Event cards can be played during the Main Phase of your turn, or during the Battle in either player's turn. When an Event is played, it is placed in the Temporary zone before it is put into Trash after its effect(s) has been resolved.