You write on parchment, paper, or some other suitable writing material and imbue it with a potent illusion containing a message.

To you and any creatures you designate when you cast the spell, the writing appears normal, written in your hand, and conveys whatever meaning you intended when you wrote the text. To all others, the writing appears as if it were written in an unknown or magickal script that is unintelligible. Alternatively, you can cause the writing to appear to be an entirely different message, written in a different hand and language, though the language must be one you know.

Should the spell be dispelled, the original script and the illusion both disappear.

A creature with Truesight can read the hidden message.

(If you have the Ritual Casting feature, then this spell can be cast as a ritual – if you increase the casting time to 10 minutes, then this spell doesn't use spell slots.)