Clear an entire area by digging through it to obtain this trophy. Yes, dig away everything, not just each square, it needs to look like the image below. Having 5 lives helps a lot. You must leave 2 enemies alive, or else the last one will just run off and the round will end. You'll probably want to keep at least one dragon around, because they will sometimes stop in their tracks to breath fire at you, which makes them easier to escape, but two of them might get you trapped sometimes.

Use your inflation attack to stun enemies, you can even walk past them while they are stunned. You may also want to save scum if you're doing really well, so you don't have to start from the beginning each attempt. See the Tips & Strategies section for how to save scum. Enemies will go slower in the beginning and after you've died, but eventually speed up quite a lot. You really shouldn't try to do it all in one life, you can have 5, save yourself a lot of hassle and use them for all they're worth.