8/25/2017 A player attacked you if that player declared a creature as an attacking creature and that creature is attacking you. If that player attacked only planeswalkers you control, that player didn¡¯t attack you. If that player¡¯s creatures were attacking you only because they were put onto the battlefield attacking or only because you were reselected as the player they were attacking, that player didn¡¯t attack you.

8/25/2017 O-Kagachi¡¯s last ability exiles only one nonland permanent, no matter how many creatures attacked you or how many times that player attacked you during their last turn.

8/25/2017 If O-Kagachi deals lethal damage to a blocking creature and also deals damage to its controller, that blocking creature is destroyed before a target is selected for O-Kagachi¡¯s last ability. It can¡¯t be exiled.