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, 17 March 2009
I have Fatina in play with a random samurai and a random shugenja. I attach A Terrible Oath to the random shugenja, and then use its action to kill the random shugenja and samurai as costs.
If I react with Fatina's ability after my samurai is destroyed to create a Ghul personality, will that personality be in play by the time A Terrible Oath resolves to receive the +2F/-1C Oath token?
Fatina Reaction: Even if Fatina is bowed, after a Personality is destroyed: Create a 2F/2C/0PH Shadowlands, Undead, Ghul Personality in your current army or your home. Lose 2 Honor.
A Terrible Oath Limited: Bow and destroy this Shugenja and one of your Samurai: Your Personalities in play gain a +2F/-1C Oath token and permanently gain Shadowlands. You can not win an Honor Victory this game.
Zen Faulkes (rules official), 17 March 2009
I have Fatina in play with a random samurai and a random shugenja. I attach A Terrible Oath to the random shugenja, and then use its action to kill the random shugenja and samurai as costs. If I react with Fatina's ability after my samurai is destroyed to create a Ghul personality, will that personality be in play by the time A Terrible Oath resolves to receive the +2F/-1C Oath token?
Yes. The Reaction is occuring during the cost payment, which is long before any effects happen.