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, 19 January 2009
Just confirming I understand correctly how does this card work, because if I'm right it seems this card is very powerful.
Daidoji Murata: Recon Open: Target two provinces. During battles at their battlefields, actions may not be taken before the Defender's first chance to take a Battle action or Pass.
Does that mean that no player is allowed to play any kind of Reaction after armies engage (including the one in Akodo Hachigoro, the Naval reaction, or Sneak Attack, but also ten or so other cards) in the provinces targeted by Murata's Open? Reactions are actions too, after all. Would the players be forbidden to even announce them? Is this effect a negation? (My guess is No, it isn't)
Dan Jacobson (rules official), 19 January 2009
Just confirming I understand correctly how does this card work, because if I'm right it seems this card is very powerful.
Daidoji Murata: Recon Open: Target two provinces. During battles at their battlefields, actions may not be taken before the Defender's first chance to take a Battle action or Pass.
Does that mean that no player is allowed to play any kind of Reaction after armies engage (including the one in Akodo Hachigoro, the Naval reaction, or Sneak Attack, but also ten or so other cards) in the provinces targeted by Murata's Open? Reactions are actions too, after all. Would the players be forbidden to even announce them? Is this effect a negation? (My guess is No, it isn't)
You are correct in your guess, and your analysis.
Reactions like the one of Akodo Hachigoro and the Naval rulebook reaction would be illegal to announce at battlefields at provinces targeted by Daidoji Murata's Open action.
May not is not a negation. See here.