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, 4 September 2013
I target my weapon-wielding Kensai with Tamori Takeshi and send him off to an attack against Yoritomo Hiromi. Hiromi proceeds to use his Battle action and destroy the unit. I react to the targeting by playing Hundred-Fold Cut and destroying the weapon as a cost (it would be destroyed anyway). Does my Kensai survive the power of Thunder or not?
Relevant text:
Yoritomo Hiromi Bowing, destruction, and movement from Battle actions Hiromi performs will not be negated or delayed. Battle: Target an enemy card without attachments, or an enemy unit, with a lower total Gold Cost than Hiromi's unit: Hiromi strikes with the power of Thunder. Destroy the target.
Tamori Takeshi Open: Target your Personality: Takeshi helps him meditate. Effects of actions the target performs will not be negated.
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.
Brook Cunningham (rules official), 4 September 2013
I target my weapon-wielding Kensai with Tamori Takeshi and send him off to an attack against Yoritomo Hiromi. Hiromi proceeds to use his Battle action and destroy the unit. I react to the targeting by playing Hundred-Fold Cut and destroying the weapon as a cost (it would be destroyed anyway). Does my Kensai survive the power of Thunder or not?
Relevant text:
Yoritomo Hiromi Bowing, destruction, and movement from Battle actions Hiromi performs will not be negated or delayed. Battle: Target an enemy card without attachments, or an enemy unit, with a lower total Gold Cost than Hiromi's unit: Hiromi strikes with the power of Thunder. Destroy the target.
Tamori Takeshi Open: Target your Personality: Takeshi helps him meditate. Effects of actions the target performs will not be negated.
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.
"Will not be negated" is not itself negation, so Hiromi wins. Hundred-Fold Cut cannot save you.