Mystery stamping is a lot of fun and easily accomplished by stampers of every skill level. Most of them are designed to be used with whatever supplies the stamper already has. There is no additional cost to participate.
I CASEd (copy and share everything, or copy and selectively edit) this one from Sharon Armstrong, an Independent Stampin'Up! Demonstrator, from her YouTube presentation, with a few editorial comments of my own. I presented this at last week's team meeting. As one might imagine, no two were alike. That's part of what makes mystery stamping so fun to me.
Below is a PDF document which you may download to try your hand at mystery stamping. I added pictures and hints, so there is no need to scroll to the end of the presentation prior to completing all the steps.