From Zelda Wiki, the Zelda encyclopedia
The Giant Buzz Blob is a mini-boss of the Color Dungeon, which can be found in Link's Awakening DX.
This boss is comparable to a regular Buzz Blob but is much larger and more formidable, and blue instead of green. Upon his defeat, the door to the Nightmare Key will open.
To defeat the Giant Buzz Blob, Link must sprinkle Magic Powder upon him. Once done, he must be struck with the sword. Throughout the battle, Giant Buzz Blob will shoot lightning bolts which the young hero must avoid.
- ↑ "Link encountered the Giant Buzz Blob while exploring the Secret Dungeon on Koholint Island." — The Great Hyrule Encyclopedia, Zelda.com