Centre action:
QuoteIf you succeed, when your opponent makes a check for an action, you may reveal the ring you chose. If their check used that ring, they suffer 3 strife.
When is this strife applied? 'When your opponent makes a check' implies as it's happening (the 'resolve strife' bit, I'd guess) whilst 'if their check used' implies after the result.
This is very important in a duel because if that strife gives you the chance for a finishing blow, whether or not the increased TN from a centre action has been resolved yet will really matter!