Agnaktor is a species of Leviathan that resides in the Volcanic Region. Its body shape is relatively unique, although there are a lot of similarities to Lagiacrus. It is noted for its remarkable ability to swim through lava and tunnel through solid volcanic rock. Its fighting style is the almost the same as a Lagiacrus when on land. It can charge at a hunter, swim straight through solid rock in order to smash into them and produce a powerful orange beam, highly reminiscent of the one produced by Gravios. Its young are called Uroktor.
While fighting above ground, the lava on Agnaktor's skin will cool off and become hardened rock, causing weapon strikes to bounce. The head and chest are often soft when the rest of its body had hardened. This is because some attacks heat these parts up. Its body will become soft again as soon as any part of it touches lava. This means using a pitfall trap will get its body soft again. The lava armor can be broken off of any part of Agnaktor's body with enough damage, allowing a hunter to attack Agnaktor regardless of whether it has come into contact with lava or not.
It seems that it needs to create a spark by clacking its teeth in order to start a flame. This produces a very noticeable warning before the fire beam. This beam also makes the chest and head soft enough to strike again, as if Agnaktor had burrowed into the lava.
Also known as fire-pike wyverns, Agnaktor use their tough beaks and great strength to burrow through rock, and sometimes even cave ceilings. Encrusted with hardened lava that can soften from the heat when they spit magma or burrow.
Also known as fire-pike wyverns, Agnaktor use their tough beaks and great strength to burrow through rock. However, their hardened-lava armor becomes soft when they burrow underground or are attacked with fire or explosives.
When low on stamina, Agnaktor will fail to produce its Heat Beam. It will then either sleep or prey on a Rhenoplos to regain stamina.
Sonic Bombs will trap Agnaktor, much like Monoblos and Diablos. Tossing a Sonic Bomb instantly after it has successfully burrowed into the ground will trap it. Also like the Monoblos and Diablos, it is immune to this effect during Rage Mode.
When a certain part of the Agnaktor is wounded, and the lava broken off, that part will not cause weapons to bounce as much even if the Agnaktor's other body parts have hardened.
If a Flash Bomb is thrown in Agnaktor's face during its 360 fire beam, it will become stunned and will crawl out of the ground.
In Monster Hunter Portable 3rd, any form of explosive damage (from Barrel Bombs to Gunlance shells/Wyvern's Fire) will heat up Agnaktor's hardened parts, making them soft again.
In Monster Hunter Portable 3rd, Agnaktor receives no damage from the Dragon element when armoured, but it becomes its main weakness when its armour has been destroyed.
In Monster Hunter Portable 3rd, High Rank Agnaktor gains a sweeping heat beam while on land, but Agnaktor only sweeps it to right, making its left flank relatively safe.
While Agnaktor is underground and a boss monster roars, it will affect the Agnaktor the same as a Sonic Bomb.
Agnaktor, and its subspecies, have the largest amount of body parts that can be broken. These include its beak, its chest, its fin, its four legs (each one can be broken individually), and its tail. (Broken, not severed.) This adds up to eight total body parts broken, not including a tail sever.
In Monster Hunter 3 Ultimate, hitting Agnaktor with a fire-elemental weapon or projectile will make its molten armor soften up.
In MH3U Agnaktor also has a new attack where it will do a singular break thrust into the ground.