358.1. Check that all chosen targets are legal.
358.2. Ensure that the outcome of the effect of this card being played would not create an illegal state. Example: Check that a spell's execution does not create a state where a Battlefield has Units controlled by 3 different players.
358.3. Ensure that the card has the appropriate permissions to be played at this timing. Example: If the state is Showdown Closed and the card was the one that Closed the state, ensure that it has [Action] or [Reaction]. Example: If the state is Closed and the card wasn't the one that Closed the state, ensure that it has [Reaction].
358.4. If the card, if continued to be played, would create an illegal state, or if a choice or action at this state is illegal, the actions taken in this process are undone and the action is cancelled.