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, 11 May 2011
I'm opposing 4 Unicorn personalities with no Force bonuses other than the Shinjo's Guidance my opponent has in play, except for Moto Jin-Sahn getting +1F from a dead guy in my discard (and I'm defending).
I target one of the other personalities with The Cost of Pride to bow him. My opponent tries to use the Guidance to redirect.
What happens?
a) he can only redirect to Jin-Sahn since after the Guidance is gone that's the only valid target b) he can redirect to anyone since he chooses targets for the Guidance's effect before paying its action costs (discarding), and... b.1) my TCoP fails because its new targeting is no longer valid b.2) my TCoP resolves as expected with the new target because I had a valid target when I announced the action c) he can discard the Guidance to attempt a redirect to another guy (not Jin-Sahn), since the Guidance doesn't have a restriction to being used, just a conditional effect. This effect (targeting change) then fails since the chosen personality is not a valid target for redirection, and... c.1) my TCoP also fails because its original targeting is no longer valid c.2) my TCoP resolves as expected with the original target because that was a valid target when I announced the action
Relevant cards: Shinjo's Guidance Kami • Unique Unicorn Clan Personalities have +1F while opposed. Reaction: When another player's Battle action would target one of your Unicorn Clan Personalities, if you are a Unicorn Clan player, discard this card: Choose another one of your Personalities. The action targets him instead, if legal.
The Cost of Pride Reaction: After a Ranged Attack targets one of your cards: Give the Ranged Attack -3 strength. Battle: Bow or straighten a target Personality whose Force is different from his base Force.
Alex Jones (rules official), 11 May 2011
I'm opposing 4 Unicorn personalities with no Force bonuses other than the Shinjo's Guidance my opponent has in play, except for Moto Jin-Sahn getting +1F from a dead guy in my discard (and I'm defending).
I target one of the other personalities with The Cost of Pride to bow him. My opponent tries to use the Guidance to redirect.
What happens?
a) he can only redirect to Jin-Sahn since after the Guidance is gone that's the only valid target b) he can redirect to anyone since he chooses targets for the Guidance's effect before paying its action costs (discarding), and... b.1) my TCoP fails because its new targeting is no longer valid b.2) my TCoP resolves as expected with the new target because I had a valid target when I announced the action c) he can discard the Guidance to attempt a redirect to another guy (not Jin-Sahn), since the Guidance doesn't have a restriction to being used, just a conditional effect. This effect (targeting change) then fails since the chosen personality is not a valid target for redirection, and... c.1) my TCoP also fails because its original targeting is no longer valid c.2) my TCoP resolves as expected with the original target because that was a valid target when I announced the action
Relevant cards: Shinjo's Guidance Kami • Unique Unicorn Clan Personalities have +1F while opposed. Reaction: When another player's Battle action would target one of your Unicorn Clan Personalities, if you are a Unicorn Clan player, discard this card: Choose another one of your Personalities. The action targets him instead, if legal.
The Cost of Pride Reaction: After a Ranged Attack targets one of your cards: Give the Ranged Attack -3 strength. Battle: Bow or straighten a target Personality whose Force is different from his base Force.
c.3) your TCoP resolves as expected with the original target because that was a valid target when you chose the target.
Note that he can choose Jin-Sahn, although he doesn't have to (I'm just being complete-ist: your description of "c" doesn't cover this option).