Let us assume an enemy spellcaster has failed their first saving throw against the Compelled Duel spell (PHB, p. 224). Thus the enemy "must make a Wisdom saving throw each time it attempts to move to a space that is more than 30 feet away from you".
Does this saving throw apply if:
They are casting Misty Step or similar to teleport more than 30 feet away from you?
They are casting Plane Shift or similar to go to another plane of existence?
And not a spell, but:
They are already more than 30 feet away from you by some mechanism, but have not passed the saving throw this turn? (For example, if enemies shove you such that you are more than 30 feet away from the target, but you have not ended your turn 30 feet or more away from the target.)