Does failing to call a judge when your opponent misses a trigger constitute a Failure to Maintain Game State (FMGS) violation in Riftbound?

Ruling: Yes, once a trigger has been missed (when another game action occurs after the trigger timing), you must call a judge immediately or it constitutes a FMGS violation. You are not required to remind your opponent of their triggers before they miss them, but once the trigger is missed and a gameplay error has occurred, you must call a judge.

Sequence:

• Player plays a card with a trigger but does not announce it
• Opponent is not required to remind them at this point
• Player takes another game action (trigger is now officially missed)
• Opponent must call a judge at this point to avoid FMGS
• Judge determines if the missed trigger was potentially beneficial and issues warnings accordingly
• At low OPL, judge decides if trigger resolves; at high OPL, opponent decides

Nuances:

• This differs from Magic: The Gathering, where not reminding opponents of missed optional triggers does not constitute FMGS
• The rule exists to prevent "he said/she said" disputes and to track missed triggers
• Players can resolve missed triggers between themselves informally at lower OPL events, and judges may use discretion about intervening
• All triggers must be announced verbally (or clearly indicated physically) - even mandatory triggers like Watcher can be missed if not announced
• Putting dice/counters on cards may constitute announcing a trigger as a shortcut