Yusuke gets a spell scroll with a brief written description of its contents (what the spell does minus the weird game mechanics text, plus a disclaimer that this is single use), as well as a box of assorted candies.

There's a note:

I think someone of your imagination might be able to put this to some interesting use. Enjoy!

[ OOC Note: Make sure you have the other players' permission before deploying illusion magicks. ]