When is a Missed Trigger penalty enforced?

A Missed Trigger penalty is enforced specifically when a non-lapsing ability is missed within a turn cycle. This means that if a player fails to remember a triggered ability that is non-lapsing during their current turn, it can lead to the enforcement of a Missed Trigger penalty.

Non-lapsing abilities are those that do not reset or disappear after they are missed; they remain relevant and can still affect the game. Because of this, if a player fails to activate or respond to such an ability during the relevant timeframe (the current turn), it constitutes the imposition of this penalty.

For example, if a player has a creature that has a triggered ability that activates at the beginning of their upkeep and they forget to use it, or it is remembered later in the game within the same turn cycle, that would be a scenario leading to the enforcement of the penalty. It emphasizes the responsibility of players to remain aware of triggered abilities and to communicate them effectively within the context of their turns.