Location:
End of Dungeon 5: The Lizard.
Attack Pattern:
Digdogger is a large, spiky ball that bounces around the room. It is initially invulnerable to most attacks.
Weakness:
The Recorder. Playing the Recorder will cause Digdogger to shrink into three smaller Digdoggers. These smaller versions are vulnerable to your sword.
Strategy:
Upon entering the boss room, immediately use your Recorder. This will cause the large Digdogger to split into three smaller, vulnerable Digdoggers. These smaller versions will bounce around the room, but they can be damaged by your sword. Focus on defeating them one by one. They are relatively easy to defeat once shrunk. Be careful to avoid contact with them as they bounce. If you don't have the Recorder, you cannot defeat Digdogger, so ensure you've acquired it from earlier in the dungeon.
Reward:
Heart Container, Triforce of Wisdom Piece 5.