Note: Some Kung Fu will specifically violate this, and will say so.
Declare your action. If your kung fu alters the number of dice you will roll, or alters your modifiers, choose to activate your techniques before rolling dice. Announce your dice. Tan Dun will be attacking Amethyst Ting, and has 5 dice, while swinging his greatsword. Tan Dun has a +25 strike modifier; this does not have to be declared to Amethyst, but a visible affect (A hurricane of sleet) should be.
Opposition chooses whether they are spending Corrupt Joss. Amethyst is rightly afraid of this attack, and spends a point of corrupt Joss.
Attacker rolls dice, including River and Xia Joss effects. Attacker does not reveal result.
Defender repeats these steps.
Compare results.
Apply retroactive effects (convert success to critical success, etc).