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, 6 June 2012
If I have a 4 F Kensai (let's say Masatane) in play with one weapon attached, and my opponent plays Engulfing Flames using a monk with Fire Tokens (let's say Togashi Meiyu), can I react with Hundred-Fold Cut to negate Masatane's destruction from the Ranged 4 Attack, or is the weapon already destroyed by Engulfing Flames' first effect by the time Masatane is targetted by the Ranged Attack (and thus the action)?
Card text: Engulfing Flames Fire • Kiho Battle: Choose your performing unbowed Monk: You may target and destroy an enemy attachment. If your Monk has any Fire tokens, Ranged 4 Attack.
Hundred-Fold Cut Reaction: After another player's action targets your performing Kensai, bow or destroy one of his Weapons: Negate his destruction from the action's effects. Battle: Bow your performing Kensai or one of his Weapons: Draw two cards.
Alex Jones (rules official), 6 June 2012
If I have a 4 F Kensai (let's say Masatane) in play with one weapon attached, and my opponent plays Engulfing Flames using a monk with Fire Tokens (let's say Togashi Meiyu), can I react with Hundred-Fold Cut to negate Masatane's destruction from the Ranged 4 Attack, or is the weapon already destroyed by Engulfing Flames' first effect by the time Masatane is targetted by the Ranged Attack (and thus the action)?
Card text: Engulfing Flames Fire • Kiho Battle: Choose your performing unbowed Monk: You may target and destroy an enemy attachment. If your Monk has any Fire tokens, Ranged 4 Attack.
Hundred-Fold Cut Reaction: After another player's action targets your performing Kensai, bow or destroy one of his Weapons: Negate his destruction from the action's effects. Battle: Bow your performing Kensai or one of his Weapons: Draw two cards.
The targeting of the Ranged attack is done during the Resolution Step of the action, which is processed in the order written. Thus, the targeting of the Ranged Attack is after the targeting and destruction of the attachment, so it is not available to be bowed as a cost of Hundred-Fold Cut.