Fireblight Ganon is a boss in The Legend of Zelda: Breath of the Wild. It is a phantom construct created by Calamity Ganon to corrupt the Divine Beast Vah Rudania, and slay the Goron Champion Daruk. Now, it serves as a boss of the dungeon that the Divine Beast's body has become.
Like the rest of the Scourges, Fireblight Ganon is a mass of solidified Malice augmented by Ancient Sheikah technology, forming the vague shape of a human's upper body. Its "face" is a tall black plate with a single blue eye, with protrusions resembling stout horns at the top. Behind the mask is a mane of wild red hair, flaring out to resemble a pair of small wings behind the monster's shoulders.
Fireblight Ganon has a burly torso and mismatched arms; its right arm is several times bulkier than its left, with a large energy sword in place of its right hand. Like the rest of the Scourges, its lower body is a mass of ancient Sheikah technology that enables it to hover over the ground.
Befitting its Goron nemesis, Fireblight Ganon is slow but strong. Most of its attacks inflict devastating damage and cover large areas, but they tend to be well-telegraphed; additionally, it is a bit slower and less prone to teleporting than the other Scourges. As with all Blight Ganons, it is weak to Guardian weapons and the Master Sword; additionally, its fire-based nature means that ice-based weapons deal extra damage against it. Link should also remember to increase his heat resistance as much as possible, lest he take gradual damage from the super-heated environment.
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; this is best dodged entirely, as the second and third slashes can still threaten Link even if he performs a Perfect Dodge. 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 makes more extensive use of its elemental powers. It starts channeling fire through its blade, causing it to glow orange and leave waves of flame in the wake of its slashes; if he cannot negate the flames with a Perfect Dodge, Link should position himself between the flames in order to avoid damage. It also uses a new fireball attack that sends a single large projectile to explode on contact with the ground, covering a wide area for massive damage. Link can counter this move by throwing a Remote Bomb at Fireblight Ganon when it raises its left arm and starts sucking in air; by detonating the bomb when it is caught in the vortex, the hero can disrupt the monster's attack while stunning it and inflicting heavy damage. Alternately, he can fire an arrow at the fireball to detonate it early, hopefully catching Fireblight Ganon in the process At the start of the 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 Fireblight Ganon's health is depleted, it explodes in a burst of Malice and violet light, leaving behind a Heart Container for Link to collect as he purifies Vah Rudania and frees Daruk's spirit.
If Link rushes off to Hyrule Castle before freeing Vah Rudania, Fireblight Ganon will appear to fight Link alongside the other undefeated Scourges in a back-to-back boss battle.
Like the other blights, Fireblight Ganon seems to be specifically made to counter Daruk's abilities. It is a heavy hitter like Daruk and his Boulder Breaker. It draws power from Death Mountain just like Vah Rudania. It even has a twisted version of Daruk's Protection which allows him to charge a very powerful attack that requires a shield to reflect which was not something Daruk fought with. This attack would likely break Daruk's Protection and do damage anyway.