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.
Situation: Courtier gets Ambushed during action phase. A battleground is created, but not at a province.
Official Question: Can you play Oppression without being at a province and the +province strength effect just fizzle since there's no province? I assume that similar to Weight the Cost, you fulfill all the effects as best you can, but unless it's mandatory targeting then the effect just fizzles. All the mandatory targets are fulfilled with targetting a Courtier and sending it home.
Your assumption is correct: you can play Oppression without being at a province and the strength bonus fails.
This is a variation of a frequently asked question: Is an action legal if an effect can't happen?
Regarding this: viewtopic.php?f=59&t=88751&p=1175587&hilit=oppression#p1175587
Doesn't Oppression violates the good faith rule if none of the effects can be applied ? For example, if he player knows beforehand that there is no province there and if there is no dishonored personality during an Ambush?
Doesn't Oppression violates the good faith rule if none of the effects can be applied ?
That's not the Good Faith Rule.
http://rules.l5r.com/CE_Abilities_and_a ... Faith_Rule: "When an action is announced, the player must be able to target all required targets..." Oppression has no targets, so that's not a problem.
"meet all conditions of the action..." Oppression has no conditions, so that's not a problem.
"and pay all mandatory costs(.)" Oppression only cost is to move a Courtier home, so that's not a problem.
The Good Faith Rule says nothing about effects happening.