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 January 2009
Assume I am playing a deck that has (say) five boxable personalities on the table. I play One More Sacrifice on my turn, destroying a personality per the cost. I now have four boxable personalities in play. My turn ends. On his turn, my opponent plays Fury of the Dark Lord. My four boxable personalities are destroyed by the effect of Fury of the Dark Lord. Am I correct in saying that I would get to destroy four of my opponent's personalities of my choice, per the ongoing effect of One More Sacrifice? I am assuming that the destruction of my boxable personalities is each a separate but simultaneous effect, and that the destruction of each of my opponent's personalities is, likewise a separate, simultaneous effect.
One More Sacrifice
Limited: Destroy a target Personality you control: Until the start of your next turn, after each time another player's card effect destroys or bows a Personality you control outside the Attack Phase, you may target a Personality the other player controls and apply the same effect to him.
Fury of the Dark Lord
Limited: Destroy each Personality with a base Gold Cost equal to or less than his controller’s Stronghold’s Gold Production plus 2. Remove all Personalities in discard piles from the game.
Brook Cunningham (rules official), 6 January 2009
Assume I am playing a deck that has (say) five boxable personalities on the table. I play One More Sacrifice on my turn, destroying a personality per the cost. I now have four boxable personalities in play. My turn ends. On his turn, my opponent plays Fury of the Dark Lord. My four boxable personalities are destroyed by the effect of Fury of the Dark Lord. Am I correct in saying that I would get to destroy four of my opponent's personalities of my choice, per the ongoing effect of One More Sacrifice?
That's correct.
I am assuming that the destruction of my boxable personalities is each a separate but simultaneous effect, and that the destruction of each of my opponent's personalities is, likewise a separate, simultaneous effect.
The first assumption is correct, the second is not.
Each of your opponent's Personalities' destruction is a separate, indefinite conditional effect from One More Sacrifice's ongoing effect, all with the same simultaneous trigger (your boxables' destructions). Per Resolving timing conflicts, Step D, "The active player decides the order in which more than one [indefinite conditional effect] apply[s].""