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.
A player, 29 August 2008
Relevant cards:
Doji Chitose Crane Clan • Courtier • Samurai • Gunso Reaction: Even if Chitose is bowed, after a Political action resolves: Move your target Personality to Chitose's location. Straighten the target if he moved.
Misdirection Focus Effect: You may shuffle up to 3 Personalities from your discard pile into your Dynasty deck. Political Gozoku Reaction: Before another player would choose targets for one of his action’s effects during a battle, target one of your Courtier or Gozoku Personalities: You choose the targets instead.
My Doji Chitose is at home, and I've got two defending personalities at the current battlefield.
My opponent announces his battle action, e.g. a First and Final Strike, or Ruthless Advance (or any Battle action that will target one of my defending cards). I don't want my defending personality to die, so I play a Misdirection (Chitose pays the cost) from my hand and choose a target for my opponent's action, then react to Misdirection with Doji Chitose (who is safe at home) and move home the chosen target.
Does the action resolve, or does the action fail due to my interference with mandatory targeting (moving home the target for my opponent's action)?
Relevant rules text:
From the point when an action is announced legally, to the point after reactions to a particular targeting have taken place, if anything interferes so that the particular required targeting can no longer be met (including reactions to the targeting itself), the action fails. Its effects do not resolve, further targeting does not take place, and its costs are waived. It is still considered taken, but not resolved. If it was on an Action card, the card is discarded normally. [CLARIFIED Feb 5 2008; each piece of targeting is considered separately]
EDIT: The point is whether Chitose's reaction happens during the timing window, or later.
A player, 30 August 2008
My Doji Chitose is at home, and I've got two defending personalities at the current battlefield. My opponent announces his battle action [...] so I play a Misdirection and choose a target for my opponent's action, then react to Misdirection with Doji Chitose and move home the chosen target.
Aside: Misdirection's Reaction's costs consist of a Gold cost of zero (the Action card's Gold Cost). Targeting one of your Courtier or Gozoku Personalities is not a cost, even if the text is in the constraints block; it denotes performing.
There is a mistake in the sequence you described: Doji Chitose's Reaction is not taken after you chose a target for your opponent's action. Here is what happens. You play Misdirection before your opponent would choose targets for his action's effects, which happens at a specific timing point (see Misdirection's rulings). When your Reaction resolves, its effect allows you to choose the targets for your opponent's action's effects but that choices are not done immediately, they are done when your opponent would have done them. After Misdirection resolves, you may take your Doji Chitose's Reaction in order to move one of your two defending Personalities home. Then your opponent's action proceeds and you get to choose the targets for its effects.
If his action is "a First and Final Strike, or Ruthless Advance (or any Battle action that will target one of my defending cards)" as you supposed, then there is still one defending Personality left at the current battlefield so you must choose her. However if there was only one defending Personality at the current battlefield before you played Misdirection and if you used Doji Chitose's Reaction in order to move her home, then there is no legal required target for your opponent's action and the rule that you quoted must be applied: "the action fails. Its effects do not resolve, further targeting does not take place, and its costs are waived. It is still considered taken, but not resolved. If it was on an Action card, the card is discarded normally."