There's a decent chance that you'll unlock this by time you complete the game, but here is a surefire way to do so (with the help of a little luck).
First, you are gonna want to start a new game and reach level 3 with no upgrades. You will start by fighting a granny.
To get the Little Orphan Granny down to 1 health, you will need to do exactly this (you should be able to re-roll until you get what you want, as long as you don't die):
First word - 3 bronzes, 1 silver = 28 damage
Second word (the annoying one) - 3 normal bronzes, 1 Cracked Tile bronze, and 1 silver = 29 damage
Third word - 2 bronze, 1 silver = 22 damage
I can no longer get the above method to work because I now do one more damage with the third word, but I have a new way to do it. It is a little more annoying though.
The first word is inconsistent for some reason that I haven't quite figured out, but it doesn't take to long to keep resetting until you get 37 damage using the combination. After that, it should be fine. (I get 22 using the second word
almost every time)
First word: 2 silvers, 3 bronze - 37 damage
Second word: 1 silver, 1 cracked bronze, 2 normal bronze - 22 damage
Third word: 3 bronze - 20 damage