Like all bosses who fight in Breath of the Wild, Fireblight Ganon divides its attacks into two phases – one when its health is above 50%, and the other when it is lower.
FIREBLIGHT GANON PHASE 1
The trick to defeating Fireblight Ganon is getting close. Down below, he doesn’t have much attack or defense to do.
If you’re not under him, and he’s making sweeping or other sword attacks, block him or try to walk away from him when he does. If he’s shooting fireballs, run behind poles for cover.
With the Master Sword, it doesn’t take much to undermine his health below 50 percent and start the second stage.
FIREBLIGHT GANON PHASE 2
The second stage of Fireblight Ganon revolves around as he hangs over you, throwing one big fireball.
If you follow along with our guide above, you should have a good stock of ice arrows at the ready (from treasure chests in Divine Beast Vah Rudania). One shot with them will destroy the fireball. If you don’t have any ice arrows, just hide behind large objects to avoid getting hit.
Do not attempt to attack while surrounded by Yellow Orb. Nothing will surpass it. Excludes …
To create a fireball, Fireblight Ganon absorbs everything around it. This is the key to breaking the attack. Throw a remote bomb on his way, and detonate it. This will break his armor and make him vulnerable to attack.
Once again, with the Master Sword, it descends quickly. He still has some of his earlier attacks (reinforced by a flame on the ground), and your best bet is to avoid them, block them, and at every opportunity you make your way under them, where he is more vulnerable, and you are the best able to attack him.
Hurt him enough, and he will fall to the ground. This is your chance to unleash your every attack.
COMPLETING THE DIVINE BEAST VAH RUDANIA MAIN QUEST
Defeat Fireblight Ganon, and you’ll get a Heart Container. You will also receive Daruk protection, which will “automatically protect you from all kinds of attacks as long as you own the ZL”.
After a movie scene, the city of Gurun will be tarnished. You must talk to Bludo to complete Divine Beast Vah Rudania’s mission. On your way, you will come across Yunobu for no good reason. Just walk straight ahead, and talk to the boss.
After your conversation, enter Bludo’s house (behind him), and open the treasure chest there for the Boulder Breaker, a powerful two-handed weapon.