A topic from AEG's L5R CCG Rules forum, copied for Oracle of the Void from a copy of the forum saved in October 2015, so pages it didn't save are missing. Players' names are left out; the rules officials are named. Rulings are as they stood on these dates; later rulings, the rulebooks and the Rules Archive may differ.
Oneiyara has not won a duel this turn yet. Can I Interrupt Oneiyara's Battle action with Personal Dojo when I'm in the middle of using his Battle action? What will the result be?
Oneiyara Iaijutsu Battle: Oneiyara challenges a target enemy Personality. After the duel, Fear equal to Oneiyara's Force that targets the loser.
Personal Dojo Tireless Interrupt: If you have won a duel this turn, each of the action's Fear effects have +1 strength and may target Items and Spells.
Oneiyara has not won a duel this turn yet. Can I Interrupt Oneiyara's Battle action with Personal Dojo when I'm in the middle of using his Battle action? What will the result be?
Oneiyara Iaijutsu Battle: Oneiyara challenges a target enemy Personality. After the duel, Fear equal to Oneiyara's Force that targets the loser.
Personal Dojo Tireless Interrupt: If you have won a duel this turn, each of the action's Fear effects have +1 strength and may target Items and Spells.
According to the Good Faith Rule: To legally announce an action, a player must be able to: 3. meet the conditions of any phrase beginning with “If” that starts the action’s effects (such as “If you are the Attacker, …”).
If you have not yet won a duel this turn, you may not announce Personal Dojo's action; if you have won a duel this turn, you may announce the action. It does not matter whether or not Oneiyara has won a duel yet this turn.