Can Isawa Zao use his reaction even if the spell he is casting requires him to bow?
Isawa Zao Reaction: After Zao performs a Spell or Kiho: Give Zao +2F or gain 2 Honor.
Thanks,
-Steven
Isawa Zao
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.
Can Isawa Zao use his reaction even if the spell he is casting requires him to bow?
Please take care that "casting a Spell" has no meaning in Samurai. Assuming you mean: "Can Isawa Zao use his reaction if he is performing an action from one of his attached Spell with a cost of bowing him?" then yes his Reaction can be taken, because the timing point "after Zao performs" takes place after the action is announced, because the performing is from a Spell attached to Zao (see Glossary, Perform).
Since mandatory costs are always paid after mandatory targets are chosen when playing an action, the answer would be the same for a Spell like The End is Near even if its action targets Zao while the Spell is not attached to him, because the timing point "after Zao performs" takes place after the action targets him (in the constraints block). The answer is also the same for Essence of Gaki-do because Zao would still be targeted (in the constraints block) before he bows.
At last, please use the search function before raising new questions: see "Isawa Zao and Reacting while bowed".