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, 9 December 2010
A shugenja has a poison token. A yojimbo has not. They're both in the same location. I target the shugenja with Mysterious Ailment. Can Final Sacrifice redirect this action onto the yojimbo? Why or why not?
Mysterious Ailment Ninja • Political Open: If you control no non-Ninja Personalities: Target a Personality with one or more Poison tokens. He is too sick to attend an important event. Bow and dishonor him. Reduce each of his controller's Honor gains by 1 until your next turn begins
Final Sacrifice Reaction: When an action would target a Personality you control, target your Yojimbo: The action targets him instead, if legal.
A player, 9 December 2010
Can Final Sacrifice redirect this action onto the yojimbo?
Final Sacrifice can be played legally but it will fail to change the targeting of Mysterious Ailment.
Why or why not?
Because the performing Yojimbo must be a legal target for Mysterious Ailment in order to have its targeting change, and this Yojimbo is not a legal target because Mysterious Ailment must target "a Personality with one or more Poison tokens" (card text) and the Yojimbo has no such token on him.