Lavasioth resembles a bipedal coelacanth fish covered in hardened lava, which forms a tough outer shell. It has two dorsal fins, two pectoral fins, two pelvic fins, and a long, thick tail to help swim through the thick lava it resides in. Its head is fish-like in nature, with rounded features and large, circular eyes. Its mouth is filled with sharp, needle-like fangs. Its powerful hind-legs end in fins rather than claws, but are capable of supporting it on land.
Its attacks and movements are vaguely similar to those of a Plesioth. It can fire huge balls of magma at hunters. When these hit the ground, they scatter into smaller molten rocks which can still do considerable damage. Lavasioth is known to use its heavy body weight to slam or crush attackers.
Lavasioth is a rarely-seen Piscine Wyvern, living and swimming in lava. Like most large monsters, it is territorial and will attack intruders on sight.
In Monster Hunter Frontier Season 8.0, HC Lavasioth was introduced, complete with several new attacks. It can rear up and fire a spread of fireballs into the air, which fall and damage hunters around it, and it can fire more projectiles from within the lava. It can also use double body-slams.
A piscine wyvern that resides in magma. Its scales are covered by layers of cooled magma, which makes it one hard nut to crack. It swims around in lava, spewing the molten rock it takes in at its prey… Researchers love to study its peculiar way of life.
Monster Hunter Generations
A piscine wyvern that resides in magma. Its scales are covered by layers of cooled magma, providing it with formidable defense. It swims around in lava, sucking in molten rock to spew at its prey. Its peculiar biology makes it a popular research subject.
Threat Level (危険度): ★★★★
Monster Hunter World
Lavasioths utilize molten lava as armor. They are extremely aggressive and will attack without prejudice until the threat has been eliminated.
Monster Hunter Frontier G
Monster Hunter Online
Threat Level (危険度): (?)
Alongside Hypnocatrice, Lavasioth is one of only two monsters originally introduced in Monster Hunter Frontier to have been officially introduced into the main Monster Hunter Series.
By extension of this, it is also one of the only Frontier monsters to have had its name officially localized to English.
Lavasioth features some minor differences between Monster Hunter Frontier and Monster Hunter Freedom Unite.
In general, the shape of its head it much more rounded and bulbous in Frontier, while in Freedom Unite, it is narrower, and with a sharper point on the snout.
This is most likely due to the fact that the Frontier Lavasioth was made on a different engine and the monster would have had to be re-modeled from scratch for Freedom unite.
In Frontier, Lavasioth will perform the same roar animation before its sliding maneuver as Diablos, Basarios, Monoblos, or Gravios will before their charge attacks.
In Freedom Unite, Lavasioth will enter the lava pool in Area 10 of the volcano and launch sets of three fireballs by jumping in and out of the lava.
Its head and back fins are breakable.
Lavasioth is weakest to cutting damage on the stomach, and impact damage on the back.
It is easy to notice when it is weak enough to capture; the layer of flowing lava on its body will disappear.
Like the Plesioth, its areas are limited. It can only move between areas 9 and 10 in the Volcano.
It can chain up to four body slams, most often when it is in rage.
Lavasioth's Hip Check is blockable, but even if blocked the Hunter will still take minor damage (even if they are using Guard +2).
Monster Hunter Freedom Unite
In the video "Magma-Swimming Wyvern", an Apceros dies when Lavasioth shoot its molten rock, and a Vespoid dies when hit by a tail swipe; but, in-game, Apceros and Vespoid will not die easily like in the video.
Monster Hunter: World
Lavasioth has been overhauled, with new moves, new behavior, new animations, and a new armor mechanic.
Lavasioth's lava shell will cool as it stays out of magma, similarly to Agnaktor. When the lava cools, attacks will bounce off and elements become less effective.
The lava shell can be forcefully softened by using a Torch Pod or a fire element attack.
Lavasioth's tail can now be wounded.
During the later half of Monster Hunter: World's first anniversary event, a unique Lavasioth that drops decoration jewel as shinies can be fought in the event quest "My Name is Lavasioth"
According to the Developer Diary of said event, Lavasioth was chosen specifically for that quest format because it is the least hunted monster by players at the time.