Mundane to Extra. it appears to me that this works on one of the items you had, or accumulate on the level. If you throw something away, that may be the item that was going to be changed. If you haven't finished the level, then an as of yet undiscovered item may be what is to be changed. So hint, throw away anything mundane you don't need at the end of each level, so that as you accumulate, you aren't forced to toss the one that was going to change.
You should put some teaser gold into the game in the first 3-4 days so I can get some sort of feel for what investing creds would do. Wouldn't need to be over 10 gold, but just enough to get me hooked.
 "Monsters' Den: Book of Dread"){kind=icon}
 "Game of Thrones Ascent"){kind=icon}