A topic from AEG's L5R CCG Rules forum, copied for Oracle of the Void from the Wayback Machine (its copy), so posts 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, 25 June 2005
In continuation of this discussion. http://www.alderac.com/forum/viewtopic.php?t=22018
Zen's observation really intrigues me. I'm wondering if, at the time the Void Dragon's reaction is performed, I have fewer cards than my opponent, will he have to discard his whole hand (assuming that Sezaru Returns is in effect)? It's well-established that cards are drawn one at a time, and I had mentally always thought the same thing about discards, but there is no precedent for that opinion. Any chance for a ruling?
I assume this ruling will also extend to First Wedding. I tell my opponent to discard a total FV of 4. Can he start pitching and then stop once he gets down to my hand size?
Zen Faulkes (rules official), 25 June 2005
It's well-established that cards are drawn one at a time, and I had mentally always thought the same thing about discards, but there is no precedent for that opinion.
Having thought about it a bit more, I remember some rulings on New Year's Celbration that if you had to discard you hand, you could not discard them one at a time (i.e., you couldn't use it to play old school Ring of the Void).
So, if you are forced to discard "all your cards" or "your hand," Sezaru Returns wll stop all discards.