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, 27 August 2012
Hi,
Can I use the rinh of earth ability on battelfield created by ambush?
Ring:: Battle: Even if you control no units at the current battlefield, bow this card or discard it from your hand: Give a province +3 or -3 strength.
Ambush: Limited: Choose your performing unbowed Personality and target another player's Personality: Create a battlefield (not at any province). Assign your Personality to attack there. Assign the target to defend there, even if he is bowed. Other Personalities will not move there. Fight a battle there (after this action's resolution). After the battle ends, lose 5 Honor.
I think I can becous the cost is just to bow the ring:)
Thx for reply
Alex Jones (rules official), 28 August 2012
Hi,
Can I use the rinh of earth ability on battelfield created by ambush?
Ring:: Battle: Even if you control no units at the current battlefield, bow this card or discard it from your hand: Give a province +3 or -3 strength.
Ambush: Limited: Choose your performing unbowed Personality and target another player's Personality: Create a battlefield (not at any province). Assign your Personality to attack there. Assign the target to defend there, even if he is bowed. Other Personalities will not move there. Fight a battle there (after this action's resolution). After the battle ends, lose 5 Honor.
I think I can becous the cost is just to bow the ring:)
Thx for reply
Yes.
The Good Faith Rule states: When an action is announced, the player must be able to choose all its explicit performers, target all required targets, meet all conditions of the action, and pay all mandatory costs, to the best of his or her knowledge. If the action involves putting one or more cards into play as a non-optional effect, the player must be able to meet all costs and requirements to bring those cards into play legally, in order to meet the Good Faith rule. This includes having a Personality who can legally attach any attachments to be brought into play.
Ring of Earth's ability does not bring any cards into play, so the second paragraph is irrelevant. There are no performers and no targets. The only cost is to "bow [the ring] or discard it from your hand". There are no conditions in the constraints block, so that just leaves the Rules of Presence and Location. Presence is always satisfied because of the text "Even if you control no units at the current battlefield." Location is irrelevant because the action is not performed, it has no targets, and it's not from a card in a unit.
So, as long as it's your opportunity to take a battle action or pass, you may use Ring of Earth's ability.