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, 13 April 2009
I have a dishonored Shugenja at a battle. Unexpected Betrayal has been played on him. I control a samurai at the battle. Can I play master of the rolling river with the shugenja, with determination so I can in good faith expect my action to suceed, or am I prevented from paying the cost of bowing and there by not able to announce the action in good faith that it will be sucessful.
The essence of the question is this: Does determination look strictly at effects or does it allow you to pay costs that you would otherwise be unable to pay, in that case have a shugenja bow as a cost even though they are prevented from preforming actions.
Thank you.
Zen Faulkes (rules official), 13 April 2009
I have a dishonored Shugenja at a battle. Unexpected Betrayal has been played on him. I control a samurai at the battle. Can I play master of the rolling river with the shugenja, with determination so I can in good faith expect my action to suceed, or am I prevented from paying the cost of bowing and there by not able to announce the action in good faith that it will be sucessful.
The essence of the question is this: Does determination look strictly at effects or does it allow you to pay costs that you would otherwise be unable to pay, in that case have a shugenja bow as a cost even though they are prevented from preforming actions.
Thank you.
Determination reads, "The action cannot have its effects negated or have its targeting changed."
Determination does not interact with costs (unless targeting was involved, and even then it would only prevent the targeting from sliding around).
Brook Cunningham (rules official), 13 April 2009
Additionally: Unexpected Betrayal doesn't actually negate anything.
The reason is, performance isn't determined by cost payment; it's determined by taking an action on the card itself, or one of the card's attached Spells or items, or by the card being targeted in an action's constraints. And,
http://rules.l5r.com/Glossary_C#Cannot (emphases mine): "In card text, when referring to entering play, targeting, attaching, using a trait, or taking an action, "cannot" is a restriction on the legality of that thing in the first place, not negation of its effects."
As you can see by my emphases above, in either case of the determining of performance, Unexpected Betrayal's "cannot" is a prohibition upon the legality of taking the action at all (not a negation of payment, as the original poster assumed).