After an adventurous journey filled with tons of threats as well as surprises, players will need to confront the Demon King himself as part of the Destroy Ganondorf quest in Legend of Zelda: Tears of the Kingdom. As with most of the main quests in the game, it is quite crucial that you prepare before you jump into the quest. Importantly, your goal should be to equip yourself against Gloom, which is going to be your biggest hurdle in the battle.
The first way is to equip Gloom Resistant armor, which is the Depths Armor Set, that can help you tackle Gloom to some extent. You can learn more about how to get the Depth Armor set in our guide here. On top of that, you need to ensure that your recipes have Sundelions in them, which will allow you to get back the hearts that you lose due to Gloom. Apart from that, you can complete some shrines to ensure that you have enough Heart Containers.
Reaching Demon King Ganondorf
Before you can confront the Demon King, you need to first find him. He resides beneath the Hyrule Castle, so you need to divide right into the Hyrule Castle Chasm. You can do so by simply fast traveling to the Serutabomac Shrine and making your way to the Chasm from there. Right after you jump in, you can head towards the north to find the Cambobatures Lightroom at -0178, 1167, -0515, which will allow you to quickly fast travel to the area. Continue downwards after activating the Lightroot to reach the Gloom's Approach.
After reaching the bottom, turn around towards the South to find a cliff. There will be multiple Shock Likes, so you need to be wary of that. Avoid them and continue gliding forward toward the South to reach a room with Horriblins. You can safely avoid these and keep heading toward the South to find a wall that you can climb. When you reach the top, you can choose to kill or simply avoid the Electric Keese here, and head towards the east to reach a ledge. Keep going forward and the floor with break down, taking you along with it. Towards the east, you will find another area where the floor is falling, but this time you need to jump on top of one section and use Recall to get back up.
How To Defeat Gloom Hands & Phantom Ganon
Continue following the path to reach another with Frost Likes on the South. Avoid them and continue forward to reach another area with the floor falling. Once you reach the bottom, the sages will disappear, and you will need to defeat Lizalfos here. There are two important areas here to prepare you for the battle. On the left, there is a room filled with Zonai equipment while the area on the right has a few more weapons. Continue towards the South to reach an area with Gloom Hands.
As with the previous ones, you can use Bomb Flower to take them out. It is quite crucial to maintain your distance while dealing with Gloom Hands, as you can get swarmed by them before you even realize it. It's best to strike early with your Bomb Flower, so make sure you have them ready as soon as you reach the area.
Once they are defeated, Phantom Ganon will spawn, and you can defeat it using the same strategy - wait for it to attack, perform a dodge, and use a flurry attack to get its health down. Obviously, you can avoid them and simply grab the wing towards the west to continue forward, but the Phantom Ganon can help you get the Demon King's Bow and a Gloom Spear if that's something you are interested in.
Traversing the Forgotten Foundations
Head left towards the North to find a glowing path, which is the Forgotten Foundations. Continue forward and use your fused weapons to break the wall in front of you. This will bring you back to the area you see at the start, and you can continue forward by breaking the wall on the east. Continue forward and then jump below to reach the Gloom's Lair.
From there, head towards the South to reach a scary-looking cliff. You will get a prompt to Jump, and once you do that, a cutscene will play after which the Demon King's Army will spawn, kicking off a long battle. You can refer to our complete guide here on defeating the Demon King Ganondorf and his army for more details. Once you have defeated him, a cutscene will play marking the end of the quest.