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, 31 January 2013
The Plain of Glass You do not lose Honor from Spider Clan and Fate cards you own. You may use the rulebook Conquest ability twice per turn during the same battle.
Player Abilities (from the Comprehensive Rules) (Conquest) Reaction: After a battle resolution ends, choose your performing attacking Conqueror Personality at that battlefield: Straighten his unit. It will not bow from the battle’s resolution.
This all worked fine and dandy until earlier today, when the Once Per Trigger rule was restored. The Plain of Glass allows a second use of the Conquest ability per battle, waiving its usual once per turn restrictions. However, it does not explicitly waive the (now extant) Once Per Trigger restriction (thus, you could Conquest two people if and only if a given battle somehow had a second battle resolution, which is not possible at least under the EE card set, if at all).
Should The Plain of Glass receive corrective technical errata to accommodate the new rule, or should this be read as an instance of the "there is always a way to use the card" quasi-rule that exempts Hidden Defenses from needing an explicit waiver of the Rule of Presence?
Alex Jones (rules official), 1 February 2013
The Plain of Glass You do not lose Honor from Spider Clan and Fate cards you own. You may use the rulebook Conquest ability twice per turn during the same battle.
Player Abilities (from the Comprehensive Rules) (Conquest) Reaction: After a battle resolution ends, choose your performing attacking Conqueror Personality at that battlefield: Straighten his unit. It will not bow from the battle’s resolution.
This all worked fine and dandy until earlier today, when the Once Per Trigger rule was restored. The Plain of Glass allows a second use of the Conquest ability per battle, waiving its usual once per turn restrictions. However, it does not explicitly waive the (now extant) Once Per Trigger restriction (thus, you could Conquest two people if and only if a given battle somehow had a second battle resolution, which is not possible at least under the EE card set, if at all).
Should The Plain of Glass receive corrective technical errata to accommodate the new rule, or should this be read as an instance of the "there is always a way to use the card" quasi-rule that exempts Hidden Defenses from needing an explicit waiver of the Rule of Presence?
The text "during the same battle" allows the Conquest ability to react twice to the same trigger, since there is only one trigger for the Conquest ability in any one battle.
Note: If the "Once per trigger" rule had been in effect while we were wording this card, it would have had different text, but it still works as is so we're not changing it.