Magecraft: Self-Burning Letters

[mystry]

A mid-level magecraft recipe that produces 'a piece of mail' (different object codewise but visually identical to actual letters), which when read, self-combusts after a few seconds.

... I rewatched mission impossible recently.

[Nana]

"What happened to your eyebrows?"

"Archmage finally wrote me back."

Please add this, it sounds amazing.