Bubble Blast

From Zelda Wiki.org

The Bubble Blast is one of Deku Link's special attacks. After receiving magic power from the Great Fairy in North Clock Town, holding down the B button puts you in first person mode, and as the bubble expands the distance and power of the attack increases.

Releasing the bubble causes it to spiral into the direction of where Deku Link was aiming. This can be used to hit nearby items and enemies, but since it moves slowly, it is not a very reliable attack. It's main use is for popping the balloon in the Clock Town sewers and knocking the Ocarina out of Skull Kid's hand. This attack also takes up magic from the Magic Meter whenever you use it.