I finally did the same. My advice for anyone else who tries: make sure you know all of the patterns, and pay close attention to the number of remaining monsters of each type. In my run, I was just barely able to find the gnome in time (0 remaining hearts and not enough XP to level), by realizing I had accounted for all of the odd-number-power monsters except for the guardians, so a 7 clue next to an even-numbered clue let me safely open the overlap.