Smog is the boss of the fifth dungeon in Oracle of Ages, Crown Dungeon. He is a giant cloud with two horns. This boss can be fairly difficult to defeat since he requires you to solve a puzzle to defeat him instead of a straightforward fight. There are four different phases in this fight, and in each of them Smog will separate into miniature versions of himself. You must join the miniatures together using the Cane of Somaria to create blocks in order to attack him. The first phase is easy: create a block above the lower-left block and the two Smogs will join together and you can slash him. In the second phase there are three Smogs. Create a block on the right side of the topmost block on the set of blocks on the left, and two of them will join together. You must then send the third Smog over to the middle platform and join it with the bigger smog, and slash it again. In the third phase, just keep moving the rightmost Smog to the left until it joins with the other one. In the fourth and final phase, the easiest strategy is to merge the two Smogs on the right together, and drive the two remaining Smogs toward the middle until they join together. With one more sword slash, Smog will finally be defeated.
As for attacks, the miniature Smogs will send out almost continuous blue tornadoes, and the large Smog will send out bolts of lightning. Both of these attacks are easily avoided by moving out of the way. It is also important to note that there is a button in the top-left corner that you can use to restart the round.