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.
[sorry for not copying in the Oracle text for the referenced cards, slow connection here...]
My opponent attacks my province A. I defend with Bayushi Muhito in province B and leave Bayushi Irezu at home.
He resolves province A. Can I use Irezu's ability targeting Muhito to move Muhito home from province B (not relevant for the battle in progress) but get Irezu to province A's battlefield (very relevant for the battle in progress) and score an additional action from Muhito's reaction?
[sorry for not copying in the Oracle text for the referenced cards, slow connection here...]
My opponent attacks my province A. I defend with Bayushi Muhito in province B and leave Bayushi Irezu at home.
He resolves province A. Can I use Irezu's ability targeting Muhito to move Muhito home from province B (not relevant for the battle in progress) but get Irezu to province A's battlefield (very relevant for the battle in progress) and score an additional action from Muhito's reaction?
No.
Irezu's ability reads: Battle: If Irezu is at home, target another Scorpion Clan Personality you control: Move him home. Move Irezu to the current battlefield.
If the battle at province A is being resolved, targeting a Personality at province B does not satisfy the Rule of Location: A card in a unit must be at the current battlefield to be targeted by, or explicitly perform, a Battle action.
Alex
PS Note that Irezu's wording would allow you to do this under the old Rule of Relevance - but note also that Kwanchai and Tangen, who were printed with the old rule, both explicitly required that the targeted Personality was at the current battlefield.