Monoblos are large hard-shelled wyverns that have the ability to dig and travel underground. Monoblos were named for the strong, singular horn protruding from their head, which is held as a prize by many hunters, as are their hearts, which are very rare.
They have a brown, rock-hard texture to their shell. There is a subspecies of the Monoblos known as the White Monoblos which are generally larger in size than their sand coloured counterparts and seen as more dangerous by hunters. Ironically, whilst their ear splitting roar is the bane of hunters they are weak to Sonic Bombs when not in Rage Mode and digging through the ground.
While they have no breath attack their roar is considered as a lethal weapon itself. They are also very physically capable, able to fight off hunters with horn-thrusts and tail-swings. Being able to tunnel beneath the sands of the Desert also means they can sneak up on any potential threats.
Monoblos are aggressive, and will attack Hunters on sight. Quick to anger, when suitably enraged their crown will become inflamed with red streaks, whilst the Monoblos itself moves faster and hits harder.
In Monster Hunter Frontier 10.0, HC Monoblos was released. Its attack power and speed are increased; its digging attack is much faster; it can perform a ground-slam immediately followed by a powerful horn thrust; and finally, it can perform a tail whip whilst sliding forwards.
HC Monoblos' horn appears longer and its body and tail are more spiky.
If not in Rage, when they dig underground, a Sonic Bomb can be used to produce an effect similar to "Pit Trapping" for around five seconds.
When a 'blos wyvern charges into a wall or ledge, their horn(s) causes them to get stuck in it, after two or three times the horn(s) will break and become an award item at the quest's end. Once its horn(s) has been broken, that individual 'blos will not get stuck in any wall or ledge again. Their tails can also be severed from the body.
When a Monoblos is ledged for the first time in the battle, it will yield a 'shiny' item. This can either be 'wyvern tears' or another item of that ilk. However it is possible that the Monoblos may drop a rare 'Monoblos heart'. How the Monoblos's heart is dropped is a mystery.
"Monoblos" means "One Horned" in Latin. "Mono" the meaning for 'one' and "blos" meaning 'horned'.
Monoblos are only fought in Village Quests in any MH game they are in (currently generations 1 & 2 only); i.e.: it is impossible to find a Quest featuring a Monoblos in the Guild Hall in any game.
Although in Monster Hunter 3 Diablos was confirmed to be a herbivore, it is unknown whether or not Monoblos is a herbivore, carnivore, or quite possibly, omnivore. The idea of it eating plants is, however, supported by its head being shaped like that of a Styracosaurus, a herbivorous dinosaur.
The Old Desert's music theme "真紅の角 (Crimson Horn)" is made for Monoblos.
In a quest you are able to get more than one Monoblos Heart, by this some people presume that Monoblos actually have multiple hearts, but this is unlikely for it actually a game mechanic & not actually mentioned in-game in any of the games. (Some people think that Diablos might or might not have many hearts like Monoblos, in Monster Hunter 3 Ultimate from either Diablos you can get a Diablos Heart as a rare commodity & by chance you can get two, but still this not actual proof that blos' got more than one heart.)
Monoblos gains a new attack in High Rank quests: it growls at the hunter, as it does when it first spots them, before charging at twice its normal speed. However, the speed of this attack doesn't increase in rage mode.