Without a doubt my luckiest run to date. At 1:28, I found and used a small pink potion which "helps find better things in containers". I'm still not entirely sure what that means, but it must give you some minuscule chance at finding a Midas book.

I'm not really happy with my inventorying speed after finding the Midas book cause I was so surprised I couldn't even think. But it's difficult to stress just how incredibly rare finding the Midas book in a container is... especially at floor 4. I may never get luck like this again though so overall I'm more than satisfied.