Austen's Silver Pen

You write a letter arguing for a course of action on the part of the reader, making a persuasion check. The letter must be worded in such a manner as to make the course of action sound reasonable; suggesting that the reader stab themselves, throw themselves onto a spear, immolate themselves, or do some other obviously harmful act will render the letter ineffective.

Any creature which reads the letter must make a Wisdom save with a DC equal to your persuasion check at the time of composition. On a failure, it pursues the course of action you described to the best of its ability, until either the activity is complete or 24 hours have passed since it last read the letter. If the reader comes to harm due to following that course of action, the effect on that creature ends.

Creatures that can't be charmed are immune to this effect, and will perceive the letter just as a piece of persuasive writing. Creatures which cannot read your language, or which cannot read at all, are also immune.

If the letter is torn, pierced, burned or otherwise damaged or destroyed, the spell ends.