User blog comment:Kogath/Monster Hunter: World Discussion/@comment-6050823-20190522135306

Things You May Not Know About Vaal Hazak (Sources: Dive to Monster Hunter World - pg. 354 to 359)

Length: 2095.4cm

Height: 712.05cm

Foot Size: 158cm


 * Vaal Hazak was first sighted by the Third Fleet over twenty years ago but was never seen again until the latest Elder Crossing. After Zorah Magdaros's death, and Xeno'jiiva's pulsing power, the surging energy in the New World caused multiple monsters to come out of hiding and become more active, including Vaal Hazak.
 * Odogaron is often seen as the apex or lord of the Rotten Vale, but Vaal Hazak is considered to be the true ruler of that environment.
 * The Rotten Vale is home to the effluvium. This unique bacteria decomposes organic material, including corpses, in the ecosystem in order to gain energy and breed. Most creatures, including humans, can't handle being in it, but Vaal Hazak sustains itself on it. Vaal Hazak doesn’t hunt for prey, rather it breaks down organic matter, sucks up the nutrient-filled effluvium, and converts that meal into energy.
 * Vaal Hazak is capable of storing large amounts of effluvium in its body.
 * Besides feeding on the effluvium, Vaal Hazak is able to manipulate the bacteria when attacking other species. By using its gill-like organs, Vaal Hazak is able to spread the effluvium around its body and take it directly from other creatures covered in it.
 * Ripping chunks of meat off it lessen its abilities.
 * When Vaal Hazak sucks up effluvium from nearby creatures that are covered in the bacteria, they become sluggish and weaker as they lose vital energy before eventually die.
 * The effluvium covers the skin and blood of a monster, making them more aggressive.
 * Vaal Hazak lets smaller monsters live in its territory, so it has an extra supply of effluvium if left in a dire situation without it. Vaal Hazak can manipulate it but can't produce its own, meaning it will lose it over time as it fights and is damaged in combat. Though losing its main means of protection leaves it more vulnerable, it becomes more aggressive and faster since the deadly bacteria isn't cloaking it.
 * Most monsters fear Elder Dragons, fleeing the moment one appears in an ecosystem. When Kirin appears in the Coral Highlands, for example, Raphinos will leave their habitat to avoid it, but smaller creatures don't run from Vaal Hazak for some reason, rather they stay close to it. It's possible that Vaal Hazak is somehow controlling the monsters within its territory with the effluvium, but that's only a theory.
 * Usually, effluvium can only be found in the middle section of the Rotten Vale, but it’ll also cover other parts of it if too many corpses fall in the area at once. Large amounts of oxygen is needed for decomposition, and too much effluvium can affect the fragile ecosystem as well as monsters if left unchecked. If it wasn’t for Vaal Hazak, the Rotten Vale would cease to exist. By feeding on the bacteria and making the tainted meat on its body a breeding ground for it, Vaal Hazak is able to maintain the bacteria’s population and spread it evenly throughout its environment.
 * Vaal Hazak is known to appear when the effluvium thickens throughout the Rotten Vale.
 * Vaal Hazak is called the Corpse Coat Dragon from it covering its body in rotten flesh that it has devoured. It uses that tainted meat to produce effluvium for itself, and it leaves a large amount of it in its nest (Zone 16).
 * Vaal Hazak doesn't need to move often to feed when there is enough effluvium around, which is likely the reason why it is rarely ever seen.
 * Without the flesh on its body, Vaal Hazak is revealed to have silver scales.
 * The spikes on its body are used for attaching flesh.
 * Inside of Vaal Hazak's mouth is an extra jaw that isn't used for ripping flesh, but for holding down prey. It doesn’t need to swallow prey whole, it just needs to capture its victim with its extendable jaws and pull them into the hidden ones before using its effluvium. If the monster it caught doesn’t die from the bacteria, then it'll become a new medium for Vaal Hazak to use in the future.
 * Its temporomandibular joint allows Vaal Hazak's mouth to open extremely wide, meaning it can capture larger monsters.