- Order: Leviathan
- Suborder: Leviathan
- Infraorder: Flame Wyvern
- Family: Agnaktor
Agnaktor is at the top of the food chain in the Volcano. Common prey for the Leviathans are Rhenoplos, Slagtoth, and Apceros. Despite its role in the food chain, Agnaktor competes with other large predators. These predators include Rathalos, Brute Tigrex, Stygian Zinogre, Lavasioth, Glavenus, and Brachydios. Brachydios are one of the few monsters actually seen killing an adult Agnaktor.
The average length of an adult Agnaktor is 2714.7cm. Agnaktor has developed the remarkable ability to swim through lava, meaning it can both sneak up on prey and escape from a more powerful enemy. It has a very strong beak, which it uses to burrow straight through hard volcanic rock at incredible speeds. It can even launch itself into the 'ceiling' of an area with this great speed. It also uses its beak to crack open the sturdy shells of armored prey. Agnaktor is capable of producing a powerful lava beam, which it can maneuver a full 360 degrees with its long neck. While swimming it swallows some of the lava and stores it in its body so that it can produce its powerful lava beam. Produced between Agnaktor's scales is a non-flammable substance that never burns. This substance allows Aganktor to coat its hide with lava and swim in lava. The molten rock on its body will eventually harden into a thick armor of rock, but when the Agnaktor touches lava, its coating becomes soft again. Its chest and beak armor will also soften if it fires its beam. Furthermore, its beak armor alone softens whenever it attacks by jabbing its beak through the ground, exposing it to the lava underneath. This harder coat of black rock as it cools down, as well as the softer skin armor when it heats up, may represent a tactical adaptation, trading defense for a fire element or vice-versa.
Agnaktor are reasonably aggressive. Despite Agnaktor being powerful predators, they are known to leave their habitat when a powerful monster appears or during a volcanic eruption. During the Breeding Season, both males and females will swim to the summit of an active volcano to mate, this is also where most Agnaktor learn the dig through the ceiling technique. The female will then make a nest somewhere near the top and then give live birth to 2-30 individuals at a time. Agnaktor who use the ceiling digging attack has mated at least once in their life.