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, 3 July 2012
I have out:
Tamori Kusugi (Personality) with the ability: "Battle: Even if Kusugi is not at the current battlefield, bow him: Raise or lower the current battlefield's province's strength by 4."
and
Chikushudo's Trickery 0GC Earth • Forest Open: Choose one or two of your performing unbowed Nonhuman Spirit Personalities, target another player's unbowed Personality, bow this Shugenja, and destroy this card: Create a battlefield. Negate all movement to it. Assign the target to attack there; he will not be destroyed during the battle's Combat Segment. Assign the performing Spirits to defend there. Fight a battle there.
If I have personalities at the Battlefield created by Chikushudo's Trickery, can I use Tamori Kusugi's ability (For instance, to get another Battle Action for Ring of Water), or does the lack of a province make his ability use illegal?
Alex Jones (rules official), 4 July 2012
I have out:
Tamori Kusugi (Personality) with the ability: "Battle: Even if Kusugi is not at the current battlefield, bow him: Raise or lower the current battlefield's province's strength by 4."
and
Chikushudo's Trickery 0GC Earth • Forest Open: Choose one or two of your performing unbowed Nonhuman Spirit Personalities, target another player's unbowed Personality, bow this Shugenja, and destroy this card: Create a battlefield. Negate all movement to it. Assign the target to attack there; he will not be destroyed during the battle's Combat Segment. Assign the performing Spirits to defend there. Fight a battle there.
If I have personalities at the Battlefield created by Chikushudo's Trickery, can I use Tamori Kusugi's ability (For instance, to get another Battle Action for Ring of Water), or does the lack of a province make his ability use illegal?
It's legal.
Kusugi's ability does not target the province, or otherwise refer to the province in the constraints block: the only thing that would stop you using his ability would be if you had no units at the current battlefield.