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.
Just need to settle an argument :
If I play an action performed by my Samurai that doesn't target an enemy, but grants me an additional battle action (let's use Again! as an example), is Without Mercy played before I've taken any additional battle actions, or after the action granted by Again! ? Basically if he performs his additional action granted by Again! , is it too late to play Without Mercy?
Taken from the CR: The additional action is taken at an additional opportunity to act in the current action round, before the next regular opportunity. It does not count against the normal sequence of actions in the current segment or phase; for example, an additional Battle action is taken without waiting for, or expending, the next normal chance to take a Battle action. [Changed 7 March 2013] [...] Multiple additional actions are taken in the order they are granted.
You may note that this section has changed recently (blame Without Mercy), but some points remain implicitly the same. So, even though last week I would have given a different reasoning, the answer is similar - he has to react with Without Mercy after the resolution of Again! (card text) but before he takes his additional action from Again! In any case, a Battle action always resolves fully before any additional action can be taken.