When an opponent's monster declares an attack: Target the attacking monster; negate the attack, then end the Battle Phase.
Rulings
Netrep Q&As
Q: Does “Negate Attack” stop the entire Battle Phase or just the Damage Step?
A: Negate Attack DOES stop the ENTIRE Battle Phase after it negates the opponent's attack. In other words, you are *NOT* allowed to declare any more attacks, because the Battle Phase is over due to Negate Attack. Steve Okegawa, 01/02/2004
Trap|
Counter