Who was right?
This morning a friend and I were playing a game of yugioh, and within the first few minutes of the game, we ran into an issue. He summoned a monster with an effect that increased it's attack and did not declare it. I attacked it, seeing that it read 1500 attack, rather than 2000. He said that it didnt matter when he declared it, since I attacked, but, going back to the "Fair play rules" that I remember, I was taught that if you have an effect that increases an attack, the card controller must declare it the moment the attack is increased. Of course, we argued, and he yelled at me, calling me a liar. So, I want to settle it. Who was right, me or him? Serious answers only, please.