Smog

Smog (バロム, Baromu) is the boss of the fifth dungeon in Oracle of Ages, the Crown Dungeon. He is weak to the Cane of Somaria, which can also be found in the Crown Dungeon. Once defeated, you will receive the Sacred Soil, the fifth Essence of Time.

Smog is a different type of monster than what Link has previously encountered. This monster is, like the others, willing to fight, but it is far more interested in playing games with Link, dividing itself up into two or three pieces then attacking Link while he tries to recombine the pieces. By using the Cane of Somaria to manipulate Smog's path, as well as pushing various other blocks around that Smog creates, Link can forcibly recombine Smog, attacking until it divides, then repeating the pattern. Eventually, Smog will succumb to its wounds, leaving Link victorious once again.

Strategy
Smog is immune to harm while it is split up, so Link must force the pieces back together by manipulating the blocks of the puzzle. This can be done by pushing certain blocks it lays out, but the main solving is done with the Cane of Somaria. With good timing, it is possible to move the Smog fragments on nothing but the blocks created by the cane. If a block the fragments are moving along suddenly moves, and there is no block for the Smog to move to, it will disappear, resetting to its original movement. By hitting the fragments with his sword, Link can slow them down. His sword is also capable of dispelling their attacks, except for the lightning bolt.