Your journey to find Tulin leads you to the Hebra South Summit Cave, northeast of the Rospro Pass Skyview Tower.
The entrance to Hebra South Summit Cave is at -3396, 2499, 0313, northeast of Rospro Pass Skyview Tower. There is another entrance at -3230, 2539, 0455, which is northeast of Sahirow Shrine, southwest of Talonto Peak.
Go into the cave and you will see Laissa. Go through the tunnel and be careful of the brambles. At the end you find a gust of wind. Jump over it and glide, and look north for a tunnel. Go there and follow the path. When you find some luminous ore, beware of a Horriblin to the north. Hit it in the head with an arrow to make it fall, then defeat it.
Eventually you reach a room with an unlit campfire in the middle of a pool of water. Climb up the northeast wall to reach a ledge, and continue up the wall, avoiding the brambles. At the top, there is a tunnel that goes north and a tunnel that goes east. The north tunnel has brambles in the way, and it leads to a room with a Bubbulfrog and some ore. If you went to the Bubbulfrog room, go back through the tunnel and go to the other tunnel at the top of the room that leads east.
If you go through the east tunnel, you will encounter some Pebblits. Farther ahead, you will find Gesane near a campfire. Talk to him and he will tell you to go to the lone cedar tree on top of Talonto Peak.
Go through the tunnel that Gesane showed you, and eventually you see snow falling from above. Climb up to leave the cave.
Look north and slightly east to see the lone cedar tree at the top of Talonto Peak that Gesane mentioned. That is your next destination. As you go toward it, beware of the Bokoblin and Boss Bokoblin that are patrolling the area.
At the cedar tree, talk to Tulin. If you are ready, you can help retrieve his bow. After he explains his power, talk to him to start. Glide toward the monster, and press the indicated button to get a burst of speed when you are facing the monster (you may need to press the button more than once). Then shoot the monster with an arrow. When the monster is defeated, there will be a cutscene.
Afterward, you and Tulin must fight some enemies. He will shoot at the enemies with his bow during the battle, and may also knock them down with gusts of wind. After you defeat the enemies, there will be a cutscene.
Reach the Sky Islands
Glide northeast to the stone structure across the gap. Climb partway up the stone structure and use Ascend to go to the top. Open the chest there to get a Zonaite Sword.
Continue to glide to each stone structure on the path ahead, and press the indicated button to get Tulin ready to make a gust of wind, then press the button again when you are facing the desired direction, and Tulin will blow a gust of wind. Keep an eye out for more chests on each stone structure.
One of the structures has a Soldier Construct on it. Defeat it, then climb up to the next stone structure. You can use Ascend on the far side of the structure to reach the top.
From there, go up the slope toward the quest destination. Beware of the Aerocudas up ahead, which will try to drop snowballs on you. Go up to the top of the mountain. You can talk to Huck there. Glide toward the floating stones and tap the indicated button to get a burst of speed from Tulin.
There are two stone cubes here. Move one of them to the edge near the next stone structure, then stack the other one on top. Climb up to the top of the stacked cubes, then glide from there to the next stone structure with help from Tulin.
Use Ascend to reach the higher levels of this structure. Once you reach the top, look west to see a shrine. To get there, glide to the square column near the curved platform that you are standing on. Then look southwest to see a large square platform. Glide to it, then use Ascend to reach the top of the square pillar floating above you. You are now on the Rising Island Chain.