Torchblow. What are they and why do they need a predator? This link should give you a good idea.
Basically, it's a four-legged monster, the size of a typical pig with a 1/2-inch thick shell (a shell that's seven times tougher than tooth enamel) that can run at 30 mph indefinitely (for as long as it can keep itself angry and/or excited) and breathes fire, specifically a stream of fiery gel (which is essentially coalesced flame, sticky as marshmallow and tough as rubber). Note: Unlike a regular Quad, which has the round end of the egg as its head and the point of the egg as it's "tail," Torchblow have it in reverse; the point is the head and the round end is the back.
Torchblow Attacks-Firebreath, Firebomb, and Radiance It can shoot this gel distances of up to twelve feet, and this gel is so hot it can essentially disintegrate a human tooth on contact, or in other words, it can confer enough heat (15 minute's worth of 1100 Celsius flame, according to the table in this article) on contact to destroy a human tooth. If you're wondering how much a Torchblow can spew, think garden hose.
If one gets a Torchblow really angry, or if they just feel like it, they can close their jaws tight and build up their firepower, and in five minutes their jaws will fly apart, releasing a 2x2 foot orb of fiery gel that explodes on impact, covering a 4x4 kilometer sphere (with a resulting crater where the bottom half of the sphere would be). This 'firebomb' projectile, when released, has range and speed equivalent to a medieval longbow, but it takes a Torchblow an hour to recover from that attack, and until then, they can only spew half a liter's worth of gel every two minutes, and then they can only hit something a foot away from their face, MAX.
Additionally, a Torchblow radiates as much heat as a bonfire and they glow a faint red-orange (like a fading ember) but can bring this glow to a searing, blinding intensity (enough to leave all enemies within fourteen feet lobster red and blind them for at least an hour) within three seconds. This 'radiance' attack requires two hour's recovery time before it can be used again.
Of course, Torchblow can also peck and bite; their four-section beak (actually two pairs of mandibles that fit into a cone when pressed together) allows them to peck and even lance prey, and their mandibles not only allow them to hook and clamp prey but to grab it and force it into their fiery maw. (Said mandibles are strong enough to hold and overpower a teenage girl, so do not underestimate them!) As a final 'attack', Torchblow can exert a powerful vacuum (powerful enough to pluck a Plop right from terra firma and into the fire inside it), which covers two square feet in front of them.
Torchblow Prey and Hunting Tactics
The gel-like nature of a Torchblow's flame comes from one of their three main prey items, namely Plop. Young Torchblows develop their fiery gel either by just sucking them into their fiery interiors (those are the smart ones) or by setting them on fire and then sucking them up (those are the dumb ones). This Rubberizes their flame, giving it a Plop's rubbery but sticky amorphous nature.
Young Torchblows also prey on Leafmaw (a larva-like creature, amorphous and resembling a pile of leaves, which eats mostly dumb children who try to jump into it), because they hold the Mimicry enchantment. This, as you will see, is very intelligent, but it is all instinct for them.
Additionally, in order to reduce their caloric constraints (so everything they eat isn't going into maintaining their flame), Torchblow suck up (or try to burn up, in the case of the dumb ones) Wild Anklebiters, giving their fire a 'life of its own,' so to speak, so it can fuel itself. However, flame with a life of its own also has a MIND of its own, or it would if not for the Mimicry enchantment.
You see, after being Vivified, a Torchblow's flame becomes a living flame, an elemental (AKA Farungen), but then the Mimicry enchantment kicks in. The Torchblow's magic twists to mimic the elemental inside it as said elemental is consumed, resulting in the Torchblow becoming an elemental itself (which is why they generate heat and light). However, the Mimicry enchantment also results in a Torchblow's flame mimicking the fallen elemental, creating an 'organ' of living flame, inseparably connected to the Torchblow, that it draws off of for energy and offensive power.
"What's the third prey item, though?" The answer is whatever they want! Torchblow have pig-level intelligence, a hair-trigger temper, and a distinct taste for pyromania, with a sadistic preference for living prey, specifically prey that can move and give cries of distress and a taste for arson.
Worst of all, Torchblow have the Pyris enchantment, which tends to have all kinds of nasty results on prey. It turns soft (non-rigid) organic items, like flesh, cartilage, or fur, to ash but does not destroy (or boil up) organic liquids, oils, or solids.
The Good News: Torchblow Weaknesses
Torchblows are weakened by water and oxygen deprivation, as covered in this question (look for the paragraph starting with 'however' for more on those weaknesses). Their shell can also be smashed with enough force, though I must admit I am uncertain as to whether a sledgehammer would do the job. (Pretty sure a stone brick dropped on them would though!) Their four-tube legs and eyes are also weaknesses; cut the legs, which are like rubber cement and you'll immobilize them, and if you stab them through the eyes, they're dead. (Said eyes are the size of a tennis ball squeezed into an oval shape.)
Finally, while Torchblow live in groups of up to 15 individuals, they are relatively rare, with only 5 million living individuals, and their method of reproduction makes them relatively vulnerable; like Chompers, they form buds shaped like half of an egg (with a maximum of four buds finished each month) but Torchblow buds come off when finished and drift off into the air, glowing like dull embers.
They form four of these buds each month, and while these buds are drawn to 'opposing' Torchblow buds (those complementing them, ie. those shaped like the other half of the egg they represent), these buds are often weakened or extinguished by clouds (the bud's shell has to be cracked before water can get in and kill a floating bud, so most are only weakened) or eaten by Droppers, which are of course effectively immune to Pyris, being clad in a solid shell with gelatinous insides, but which are routinely shot down and eaten by Torchblow (since they know Droppers eat their buds).
So, with all that out of the way, my question is What Would Serve As The Best Torchblow Predator?
Specifications For Best Answer:
The best answer will analyze a Torchblow's weaknesses, strengths, and abilities and determine what traits their ideal (AKA "best") predator would need to have in order to succeed. I use the word "predator" since this creature will likely be not a prey animal with good defenses that actively attacks Torchblow that come near it, but a creature that actively seeks out and preys on Torchblow. That said, I am willing to accept just about anything that can keep Torchblow in check, as long as it's not humans (they're preoccupied with their own business, you see).
The best answer will take the information in #1 and determine what predators (IRL or otherwise) would fit the bill. The only monster I have that can potentially work are Droppers, Runnark, and Snappers and that's not exactly what I'm looking for. Logic (and natural selection) dictate that if there are pyromaniacal predators around, and magic is involved, something will evolve to keep them in check and/or eat them.
The trouble is, while Enchanted monsters and creatures exist all over the place (Willful cats, Stubborn goats) I'm not sure what creature (or creatures) would serve as (or develop into) a predator capable of preying on Torchblows (or else keeping them in check). If you're wondering what animals you have to work with, my setting is based on (and therefore mirrors) medieval Europe.
Thank you, I really need to figure this out so I don't have entire ecosystems destroyed by these things.