Vah Rudania is a mechanical construct in The Legend of Zelda: Breath of the Wild. It is one of the four Divine Beasts. Vah Rudania is made from Ancient Sheikah technology; it takes the form of a giant salamander and is found on Death Mountain in the Eldin Mountains. Ganon sent Fireblight Ganon to corrupt it, transforming it into one of the main dungeons. Link must defeat this boss to free Vah Rudania.
One hundred years before the events of Breath of the Wild, Rhoam Bosphoramus Hyrule, his daughter, her Knight Link, along with four other Champions sought to seal Ganon through the use of the Divine Beasts and Guardians. Daruk, the Goron Champion, was in charge of controlling Vah Rudania.
Remembering his previous defeat at the hands of the Divine Beasts, Ganon sent out aspects of himself to subvert the Sheikah's technology with his evil power. Daruk met his demise by Fireblight Ganon, who then assumed control of Vah Rudania for the next one hundred years. Using the Divine Beast's power over fire and magma, Fireblight Ganon terrorized the Gorons with volcanic eruptions from Death Mountain.
A century after the Great Calamity, Ganon's increasing influence causes Vah Rudania to rampage the mountain once again, causing several volcanic eruptions and raising the temperature of the area to a dangerous degree, unbearable for any travelers not wearing protective gear against extreme heat. The frequent eruptions also conflict with the Gorons' mining operations, as several of the mines, used to excavate ore in order to later trade with other settlements, become far too dangerous to operate due to the amount of lava pouring down from Death Mountain's crater. To make matters worse, Ganon's influence causes dozens of monsters to nest and set up outposts dangerously close to Goron City. These events begin to directly threaten the Gorons' way of life, with decreased mining operations and the very welfare of their city and people in danger from not only the worsening eruptions, but from Vah Rudania and Ganon's monsters. If left unchecked, both Death Mountain and Goron City potentially face destruction from Vah Rudania's rampage.
Eventually, a reawakened Link sets out to free Vah Rudania from Fireblight Ganon's control. With the help of Yunobo, Daruk's grandson, the Hylian hero forces the Divine Beast into the crater of Death Mountain, allowing him to board it and slay Fireblight Ganon. This frees both Vah Rudania and the spirit of Daruk, with the latter taking control of the former once more. After giving Link his power and sending him on his way, Daruk guides Vah Rudania out of the crater, where it activates its main cannon and trains it on Hyrule Castle. Soon after, the eruptions on Death Mountain cease and the area becomes much more peaceful and safe, allowing the Gorons to resume their mining operations. When Link engages Calamity Ganon within the castle, Daruk has Vah Rudania fire a massive laser to weaken the monstrosity.
Like the other Divine Beasts, Vah Rudania's name is based on a Sage from a past installment in Legend of Zelda series. Rudania is a reference to and an anagram of the name of the Goron Sage of Fire, Darunia, from The Legend of Zelda: Ocarina of Time.
The general likeness of Vah Rudania is that of a salamander. However, some of his morphological characteristics resemble much more ancient reptiles; the large plates on his back resembling those of Stegosaurus, and the large club-like structure at the end of his tail resembling that of Ankylosaurus. This is rather fitting, as multiple bosses and enemies from the different Death Mountains from earlier games are either labelled as or appear to be dinosaurs, i.e. various incarnations of (King) Dodongo being labelled as or resembling a dinosaur.