The Fiery Jaw is the Lava Eater‘s weapon in Legendary Monsters, and it’s the one item in the mod that lets you breathe fire yourself. It’s crafted rather than dropped, so you’ll need to win the fight in the Lava Eater’s Nest before you can hold one.
Obtaining
The Fiery Jaw is a 
Crafting Table recipe, and it never turns up in 
Chest loot. Three of the nine slots are 
Lava Eater’s Skin, which nothing else in the game drops, and the Lava Eater gives exactly 3 of them every time it dies.
Looting won’t change that, the drop is a flat 3, so it works out at one kill per Jaw with nothing spare. If you want the 
Fiery Boots as well, you’ll be finding a second nest for the extra Skin.
The nest generates in Nether Wastes, and an 
Eye Of Magma made from 4 
Magma Blocks around an 
Ender Pearl will lead you to it like an 
Eye of Ender. Make two or three, as each throw can shatter at the end of its flight, and the nests sit close enough together that you won’t need more.
The nest is built from 
Blackstone and 
Basalt with Magma Blocks around the Lava, so you can pick those up on the way out. The 2 
Iron Ingots are the only part of the recipe you bring with you, as everything else is waiting in the Nether.
So the only thing that can’t be gathered on the way in is the skin, and the Lava Eater is a short fight once you’re carrying Fire Resistance. The rest of this page is about what you get for it.
Usage
Held in your main hand the Fiery Jaw behaves as an axe, with 6 attack damage at 1 attack speed, so you’re getting one full swing a second and nothing from the off hand. It counts as an iron-level tool, so it’ll strip Logs, scrape Copper and chop wood at about the pace of an 
Iron Axe.
Every hit you land also has a 50% chance of setting the target alight for 3 seconds on top of the damage. That’s a nice extra in the Overworld, though most of the Nether shrugs it off, as the FAQ below explains.
Put the swing next to the mod’s other melee weapons and it comes out low, which is the trade being made, as the right-click is where the Jaw earns its slot. It’s also fireproof as a dropped item, so a death in the Nether won’t destroy it the way a normal weapon would.
Fiery Jaw
Dinosaur Bone Club
Monstrous Anchor
On the numbers alone it’s the weakest of the three, so the Fiery Jaw isn’t a weapon you carry for the swing. It’s carried for the two abilities on the right-click, which is where the next section goes.
Abilities
One right-click fires two things at once, a shove that clears the ground around you and a stream of fire that follows wherever you aim. Both go on the same 10 second cooldown, so you can’t split them up or hold one back for later.
The Shove
3 blocks around you
Everything within 3 blocks of you is set on fire for 4 seconds and thrown along the line you’re facing, as it isn’t a radial push. A mob standing behind you gets flung past you rather than away, so turn to face the crowd before you click if you want them cleared off properly. It does no damage by itself, the fire is all it costs them.
The Fire Breath
7.5 damage a hit, 10 block cone
Alongside the shove your character starts breathing fire for about 2 and a half seconds, in a cone roughly 45 degrees wide that reaches 10 blocks once it has opened up. Anything caught in it takes 7.5 damage every time the flame connects and burns for another 3 seconds.
Each hit also cuts the target’s horizontal momentum to a quarter, which pins a charging mob in place while the rest of the stream lands on it. That’s what makes it good against things that rush you, as they stall in the cone instead of reaching you.
The cone tracks your crosshair the whole time it’s going, so you can sweep it across a line of mobs instead of committing to one. Anything that has wandered out of the cone stops taking hits, no matter how close it’s standing.
What The Breath Skips
The stream itself is picky about who it hurts. These two are left alone for as long as it’s running, whatever else happens to be standing in the cone with them, so you don’t need to worry about firing it past them.
- You, so there’s no cost to firing it point blank at something standing on top of you.
- Any tamed animal that belongs to you, which covers Wolves, Cats and Parrots, though not a Horse.
That’s the breath though. The shove that goes off at the same time isn’t nearly as careful about who it catches, and it’s the part that gets people into trouble around their own animals and Villagers.
Only the fire breath checks for your pets. The shove sets every entity in those 3 blocks alight, including your 
Wolf, your 
Horse, any 
Villager you walked in with and other players, so don’t use it inside a base or a trading hall.
The breath counts as a mob attack rather than fire damage, which matters more than it sounds. Fire-immune mobs like 
Blazes, 
Wither Skeletons and 
Magma Cubes still take the full 7.5 a hit, they just ignore the burn afterward, and that includes the Lava Eater itself if you bring the Jaw back for a second nest.
Enchantments
The Jaw takes both weapon and tool enchantments at the table, which no vanilla axe will do, so Looting is on the list alongside the usual Sharpness and Efficiency. Mending has been allowed on it as well, and with only 750 durability behind it that’s the one you’ll want most.
Unbreaking is the gap, as it won’t appear in the table’s offers at all. It has to come off an 
Anvil from a Book instead, which is a detour rather than a block if you really want it on there.
Failing Mending, an Anvil will repair it with Lava Eater’s Skin, though that costs you another trip to a nest. It’s usually cheaper to keep a spare Skin or two from the kill that made the Jaw, except that the recipe eats all 3 of them.
Other Uses For Lava Eater’s Skin
Nothing in the mod uses the Fiery Jaw as an ingredient, it’s the end of that line. The Skin has one other recipe though, the Fiery Boots, which take 2 Lava Eater’s Skin and 2 
Magma Cream and pair with the Jaw reasonably well.
The Boots fire on the X key and leave columns of fire behind you for about 15 seconds while you walk, on a 25 second cooldown of their own. Running them together gives you a trail that burns whatever chases you and a cone that burns whatever is in front, which is the closest thing the mod has to a fire set.
Tips
Open with the shove when something has already closed on you, as it catches everything within 3 blocks and buys you the room the breath needs to open up to its full 10. Firing it at nothing wastes the whole 10 seconds, so it’s better held until two or three mobs are actually on top of you.
Turn slowly while the breath is going, as it sticks to your crosshair for the full 2 and a half seconds and a slow sweep across a group lands far more of it than pointing at one mob. Sweeping too fast has the opposite problem, as anything that leaves the cone stops taking hits straight away.
Keep a second weapon in your hotbar for the gaps between cooldowns, since 6 damage a swing is thin against anything with armor. A 
Dinosaur Bone Club or a 
Monstrous Anchor covers the downtime, and the Jaw comes back out for the next pack.
Don’t aim the ability at a Log. Right-clicking one with the Jaw in hand strips the bark instead of firing anything, because the axe action takes priority, so aim at air, a mob or a block that does nothing when clicked, otherwise you’ll be standing there wondering why the ability never went off.
FAQ
Each Lava Eater drops exactly 3 Lava Eater’s Skin and the Jaw recipe uses all 3, so one kill gets you the weapon and nothing else. The Fiery Boots want another 2 on top of that, so that’s a second nest, and a third if you ever want to repair either of them on an Anvil.
The breath skips you and any tamed animal of yours, so you can fire it into a pile of mobs with a Wolf in there, though a Horse isn’t covered by that check. The shove is the part to watch, as it sets everything within 3 blocks alight for 4 seconds with no exceptions, pets and Villagers included.
The Jaw only offers weapon enchantments, tool enchantments and Mending at an 
Enchanting Table, and Unbreaking sits outside all three of those. An Anvil and an Unbreaking Book still works, so it’s a detour rather than a block, and Mending is the better use of the levels anyway at 750 durability.
The 7.5 damage a hit counts as a normal attack rather than fire damage, so Blazes, Wither Skeletons, 
Zombified Piglins and the Lava Eater all take it in full. What they ignore is the burn afterward and the 50% ignite on your swings, which is most of the reason the Jaw feels weaker in the Nether than it does in the Overworld.
