You make your way up Death Mountain, only to witness a three-headed monster emerge from the crater.

Take a Picture

If you have done the quest Camera Work in the Depths, you might want to take a picture of Moragia at the start of the battle.

Get a Wing

Nearby, to the east, you will see a Wing with several Fans already attached. Use Ultrahand to set it flat on the ground, and point it away from the mountain so that you can go off of the edge of the platform with it. Then check on the Controls to start flying.

Attack Moragia

Fly around and shoot Yunobo at Moragia's heads (change the camera angle to aim). Be careful to dodge the flaming boulders that Moragia spits at you. After you hit all three heads, there will be a cutscene.

Go Into the Crater

Afterward, glide down into the Death Mountain Crater where Yunobo went. You will end up in the Eldin Canyon Depths.