Legend of Zelda Skyward Sword Boss Guide.
Skyview Temple Boss: Ghirahim (First Battle)
Earth Temple Boss: Scaldera
Ancient Cistern Boss: Koloktos
Lanayru Mining Facility Boss: Moldarach
Sandship Boss: Tentalus
Fire Sanctuary Boss: Ghirahim (Second Battle)
Levias Boss: Bilocyte
Realm of the Past Boss: Ghirahim (Final)
Prior to this battle you will have to encounter an insane amount of enemies before reaching Ghirahim and Zelda. Make sure you have plenty of heart potions as you may need them. As you run down to the bottom of the Sealed Grounds, more enemies will continue to appear. The easiest way to defeat all these foes is to perform several spin attacks, but only use them when you need to and make sure you defeat the enemy blowing the horn otherwise more enemies will continue to appear. Once you reach the bottom, the battle will then begin.
You and Ghirahim will rise on a platform, use the small area to your advantage. You will need to attack him until he has fallen below to the next platform. To do so, strike him a few times leading him to the edge, don’t get too close or he will attack. Once you have knocked him down, perform a Fatal Blow. You will need to repeat this two more times to reach the next phase of the battle.
The next phase is like previous battles with him, a sword fight between the two. Make sure you have your shield equipped, once he attacks, block him and in return stroke him with your sword as he will then be vulnerable. Notice the red gem, this is his weakness, use it to your advantage.
Realm of the Past Boss: Demise
The final boss of the game is Demise and is Ghirahim’s master. His original form is known as the Imprisoned until Ghirahim successfully resurrects him. Demise will then wield Ghirahim as his sword and enter a portal. You can follow him into now but you can also be able to return to the sky to collect any needed potions or equipment before following Demise. I suggest collecting as much heart pieces and fill all your bottles with heart potion plus before the battle.
The first portion of the battle will be a sword fight between Link and Demise. Avoid his attacks as they can be pretty brutal. You will not be able to use the Skyward Strike in the first phase either, so do not rely on that attack. Get close to him (otherwise he will charge at you, taking off two hearts each time) and strike when you find an opening. It is best to pay close attention to his movements as he will block your attacks rather quickly. Hit him enough times to enter phase two of the battle.
Phase two is a lot tougher, Demise has charged up his sword and will unleash sword beams upon Link. Avoid his attacks and pay very close attention to his movements since when you blocks your attacks, you will be shocked this time around. You can now charge up you sword to perform a Skyward Strike, so you will obviously be wanting to do that. You will need to try and obtain one of the lightning bolts in doing so. Once you have charged your sword, perform a Skyward Strike and unleash it as soon as possible as he as charged up his sword as well. If he is hit by your sword beam, he will be stunned so run up and attack as much and as quick as you can. He will then fall to the ground. You will have a chance to perform a Fatal Blow, but do not attempt this yet as he will dodge it and attack you. What you need to do is hit him with three Skyward Strikes and only then he will be weak enough so you can perform the Fatal Blow on him.