Fireblight Ganon also refered as the Scourge of Divine Beast Vah Rudania is a Boss fought in Breath of the Wild. It is one of the four phantoms created by Calamity Ganon to take control of the Divine Beasts. It is fought either atop the Divine Beast Vah Rudania or in the center of Hyrule Castle if it is not already defeated. Once the four Divine Beasts are freed, the Monk Maz Koshia recreate the fight in Link's mind as part of the Final Trial. The original Fireblight Ganon is responsible for the demise of Daruk 100 years before the events of Breath of the Wild.
Fireblight Ganon is slow but strong. As with all Blight Ganons, it is weak to Sheikah weapons and the Master Sword; additionally, its fire-based nature means that ice-based weapons will deal extra damage to it. During this fight, Link must also increase its heat resistance unless he want to take gradual damage from the super-heated environment. Wooden shields and weapons will also burn if they are used during the battle, Bomb Arrow are also forbidden as they will explode as soon as they are out, which will damage Link instead of the Boss. Fireblight Ganon's main weapon is its massive blade, used for horizontal or vertical swipes against Link. These attacks can be dodged fairly easily, with a perfect dodge providing opportunities for a damaging Flurry Rush against the Boss. It can also use a spin attack that hits three times. It can also throw a cluster of small fireballs from its left hand for a ranged attack; if a ring of orange spheres appears in its open palm, Link should keep moving or find cover to minimize the risk of being burned. After losing half of its health, Fireblight Ganon starts channeling fire through its blade, a new fireball attack that sends a single large projectile to explode on contact with the ground, covering a wide area for massive damage. This last attack can be countered by throwing a Remote Bomb at Fireblight Ganon when it raises its left arm and starts sucking in air. At the start of the second phase, the boss surrounds itself with a shield similar to Daruk's Protection, which Link can dissipate by countering its charged fireball attack. After taking further damage, Fireblight Ganon starts firing lasers similar to a Guardian Stalker; Link can bounce the beams back to the boss with a Perfect Guard. Once defeated, Link will be rewarded with a Heart Container and Daruk's Protection.
Hyrule Compendium Entry
"This phantom of Ganon attacked the Divine Beast Vah Rudania and was responsible for the demise of the Champion Daruk. It attacks with a greatsword and fire magic."