When/Whenever

[Deebiia]

I was told that text like "When an instant is cast..." and "Whenever an instant is cast..." do different things. Could someone please clarify this for me?

[Dudecore]

There is no functional difference between "when" and "whenever". The "whenever" trigger condition can conceivably trigger more than once. The "when" usually means like "when this card is put in the graveyard", ect, usually indicating the trigger is one time use.