11.1 Enter the Gerudo Desert
Once you have obtained the Master Sword, warp out of the Sacred Grove and return to Lake Hylia. Climb the ladder that leads up to the cliffs on the southern edge of the lake and head for the watchtower in the distance. You will find Telma’s friend, Auru, at the top. You can get his exact location marked on your map by visiting Telma’s Bar in Castle Town. If you are having trouble finding a dungeon later on, you can do the same thing.
Talk to Auru to learn more about Arbiter’s Grounds and get Auru’s Memo. Show Auru’s Memo to Fyer and he will give you a ride to Gerudo Desert, the only way he knows how. The first time is free but if you want the Oasis Flight again you will have to pay 10 rupees.
The terrain in the desert is extremely rough, with lots of chasms. You can follow the southern edge of the desert until you find flatter ground, or use the Clawshot to grab hold of a Peahat and let it carry you over the chasms.
On the opposite side of the desert from where you start is the missing section of the Bridge of Eldin. Use the Clawshot on the Peahats to get to the top of the hill. Defeat the Shadow Beasts that appear and you can restore the bridge to normal. The new Warp Portal means you can return to the Gerudo Desert afterward. The missing section of the bridge was also blocking the entrance to the optional Cave of Ordeals, so you can explore in there as well.
11.2 Infiltrating the Bulblin Encampment
Head for the center of the desert, where some Bulblins are camped. The archers on the watchtowers will spot you from a long way off, but it is possible to snipe them from afar, especially with the Hawkeye. Clear out the monsters, then climb on one of their Bullbo mounts. Ride north until you reach a series of wooden barriers. Charge into them to smash through, dismount, and climb up the ledges in front of you.
The path to the next area is just ahead. If you enter it during the day you will be spotted by the archers on the watchtowers and you will have to fight your way through hordes of Bulblins. Enter under the cover of darkness and you can take out the sentries before they call for reinforcements. Stick with the Hero’s Bow and attack from a distance, because ordinary enemies can raise the alarm too.
The first sentry is above the entrance to the fortress: shoot it before you get close. Another Bulblin is patrolling inside the entrance so approach carefully and dispatch it as soon as it comes into view. On one side is a dead end, with a crate by a wall full of holes. You can move the crate and stand on it to shoot a Bulblin on the other side of the wall. This is completely optional, since it is one of the last enemies you would encounter otherwise.
The other direction goes uphill. Slow down before the turning and shoot the Bulblin leaning against the opposite wall. Look up and along the wall to find another sentry. Deal with the Bulblin on the other side of the tents and approach the wall ahead. There is a Bulblin patrolling behind the wall and another around the corner nearby. Defeat both of them from a distance, using cover where necessary.
Go to the spot where the last Bulblin was and look down the slope. Shoot the Bulblin at the bottom then go downhill. The path to Arbiter’s Grounds is on one side, but it is blocked by fences. On the opposite side are some locked gates. There should be one last sentry on a watchtower directly ahead of you. With the last sentry gone you can stop sneaking about.
Look for a Bulblin hanging around by the campfire and kill it to make it drop a Small Key. Pick up the key and head back to the locked gates. Go inside to find another Bullbo (alive this time). It can smash the barriers in front of Arbiter’s Grounds, but as you get close, King Bulblin emerges from the shadows and challenges you to another rematch.
11.3 Mini-Boss: King Bulblin
King Bulblin attacks slowly, but each hit will take three hearts off of your life, meaning instant death if you are doing a Three Heart Run. When he starts to wind up for a swing, move out of the way quickly! Use the Back Slice to get behind him and avoid tackling him head on.
After you beat him, King Bulblin sets fire to the building. With the Bullbo back on its feet it is time to get out of the building and break through to Arbiter’s Grounds. Dismount in front of the entrance and prepare to face the challenges inside the prison.