There are three answers to this question.

1. The largest creature ever recorded was a sea-behemoth, classified as Abyssal 12 though it referred to itself as “Celadon Rises Depths Beyond Ken”. It was allegedly the length of Callawen Island and was defeated by Coatl. The corpse lays at the bottom of the Celwen Strait.
2. The estimations of the behemoth plaguing the Abyssal Ocean range from “topping the Leviathan Scale” to “preposterously and insultingly enormous”. Of course, as its existence is tenuous at best, whether or not it can rank as the largest is up to maritime debate.
3. The largest still-alive behemoth* is found in the Western Dominion, on Bivve. It resides in the Tache Pass, where it guards the entrance near Quiet Mountain, which it considers to be part of its territory, and is generally friendly and receptive to communication. Though initially classified as Icean 1203, most refer to it as ‘Domina’ from its name ‘Ovaal Dominates, Oversees, Ever-Watches the Ice-Capped Ridges”. It is about 40 feet tall at the shoulder.

*As far as anyone who doesn't live on Evenne is concerned, at least.

Lacraya: Central Lacraya, along the Savalla, suffers from periodic flooding, though its peoples utilize this for their harvests. Blizzards swirl into a frenzy in the north, and often travel through the Canthores Mountains before dissipating into auroras in the plains. As Lacraya’s atmospheric magic is incredibly high, behemoths (enormous animals hungry for magic), puppets (objects that have become sentient), and wraiths (a magic-induced "ghost" of intense emotion or feeling that lingers in a particular area) are a constant problem.

The Isle of Shattered Stars: It is said that the Moon-Sister Lagoon protects the Isle from disaster - with good reason, as very little reaches the Isle. The worst it handles is thunderstorms during the wet seasons, and the exhausted aftermaths of Moondown’s hurricanes.

Chellabra: Dust and sandstorms plague the wastes beyond civilized Chellabra, with rock-filled avalanches punctuating the more mountainous regions. Despite its appearance, the continent never suffers droughts or famines, as their god Mewt Mavet provides for them in all ways.

Bivve: As Bivve has a variety of climates, the natural disasters vary just as heavily - floods in the Allerian lake region, earthquakes in the Western Dominion, minor eruptions in the Passane chalk flats, water spouts in the Quen Sea, etc. Overall, though, its inclement weather tends to be tamer than other continents’, partially due to constant work by weather teams.

Moondown: Typhoons regularly shred through the Moondown coasts, beginning in the west and making their way east towards Iah-Yah and Sarens. “Junglestorms” are also common, when the Maiden’s Tangle whips itself into a frenzy and begins quickly reclaiming any structures or cleared land within reach. Junglestorms can last for weeks, though they’re more common in the summer, and require ample manpower to combat. In Iah-Yah's badlands areas, volcanic activity is common and eruptions can occur year-round.

Cadava: Acid rain. Though surrounded by water, the Seeplands and Worldshear’s toxic liquids are usually the first to rain back down on the glacial tundras. In the coastal regions, random flooding from melting glaciers eats at the beaches.

To the Ardor, the rainbow is a symbol of Yerxes, representing his prism-Flames, which encompass all colors of the world. As such, they are seen as omens of primarily good luck, or Yerxes' blessing on an area. It is common for people to go gambling or take risks after seeing a rainbow.

To other religions, they are not associated with any god or concept, but are sometimes seen as good fortune - believed to be bleedover from Ardor myth. Sometimes they are attributed to Vemeter, herald of magic, but this is less common.

The Abyssal Ocean is a constant source of fear and apprehension. It consumes all vessels that dare to tread into its waters, almost like the sea itself is alive. Reports of ships toeing its border speak of enormous tentacles and black masses, and seemingly a sheer drop into nothingness past that - but due to high magic saturation in the area, these accounts may merely be induced hallucinations. Still, it has captivated the minds of many citizens, and there are dozens of cautious folktales and scary campfire stories told about it.

It is a real threat to sailors, however, especially from Lacraya and Chellabra. None who have set foot on a ship passing the Abyssal would ever joke about its supposed terrors.

Magery is not necessarily a rare art, as much of Flameverse is magically-saturated. This means there is more raw Magninium in the air than can be spent or absorbed by the world, and so magic is easier to use and magical events are more common. Such, mages find it easier to control their craft and influence what's around them.

Most mages will study under another mage in less organized countries, like the Holy Empire or Cirshiva. They will typically operate as freelancers or nomads, traveling the country to offer their services in return for money or goods. Some may end up employed in the military or behemoth-fighter's guilds, protecting regions from outside threats. They are a mix of all three mage types - practical, combat, and medical.

In some countries, like many cities of the Western Dominion, Sarens, and Chellabra, becoming a mage is an offered career path in their educational systems. These magics are more academically-inclined, trained in traditional magical theory, and often contribute to centers of knowledge in their respective nations. These mages tend to lean towards practical magic.

In highly militaristic countries, or countries with compulsory service - such as Passane - magery is often offered as an alternative to traditional army training. These mages are specialized combat mages, trained in the art of magical warfare. The more timid may become healers or practicals, crafting magic circles for city defense or enchanting weapons for high-ranking individuals. The more... unhinged... may be used as specialty units, espionage, infiltration, or simply as talented infantry. They typically stay within the military, or go into practical magery once released.

The Vaervaen Kingdom has the most secure true prison in the world, in a secretive location within the Viavista Mountains. Not only does it hold the Vaervan’s criminals, but they willingly accept and house high-profile criminals from other Bivvian countries for a nominal fee. Though unsaid, it is presumed that they experiment on these individuals, who are typically serving life sentences.

The Fortress of Verglas, Verebriva’s capital, was also conceived as a prison originally, hosting those Marary despised and thought plotted against him. The original prison is used today as the governmental capital and Saen’s quarters (though he maintains a ‘summer home’ in privacy elsewhere).

Passane puts its criminals to work in the fields of Orchen, its agriculture powerhouse, for a number of years. Should they prove disobedient in Orchen, their magic is usually drained for use in gemstones and their bodies disposed of.

Flameverse lacks modern refrigerators, but store food in various iceboxes. More rural areas' iceboxes will likely be made underground as pits, possibly lined with ice depending on their location, and meat will be preserved through drying and salting. However, these methods fell out of fashion ages ago to mage-created iceboxes, which utilize a simple rune to cycle heat out of the box, keeping its contents cold. These boxes were originally invented in both Iah-Yah and the Vaervan Kingdom around the same time, and permeated through trade to other continents. You can even get mini-iceboxes sized like a purse or backpack to make carrying around fresh food easier.

In markets, stalls that sell cold goods or want to keep temperatures down will use huge crates with these runes inscribed on them.

This depends heavily on what country you're in.

In Iah-Yah for example, whose society is divded by a series of castes, the second-highest caste are Umersii, which are generally understood to be landowners. They are permitted to make any rules of any sort as they wish that are applied to the land that they own, but enforcing these rules can be difficult without money to hire peacekeepers or the support of the local Vetenne, the wealthiest and highest caste. In addition, their laws cannot supersede or alter the laws of the church and clergy, which apply equally across the country and are generally wide-sweeping. Umersii's land claims can be rather small; large cities may be sprawled over land owned by many Umersii who must convene to compromise on laws (or say "to hell with it" and make their own random laws that change depending which street you're on).

In most other countries, the land is wholly owned by the central government (Passane, most of the Allerian Union, technically the Holy Empire, Maweth) which "rents" out the land to varying levels of society - basically feudalism. The Holy Empire maintains that the Emperor owns all of the land of the country, but holds a law allowing the people of the Empire to do it as they need to survive, which is enforced by the local Flames (who generally make sure nobody's over-hunting or using unsustainable farming).

Tashen is one of few countries that allows the "common person" to buy and own land (AKA it's not seen as socially odd and is not frighteningly expensive), but most people would only own a plot around their home. This law does not extend to the open waters of the Quen Sea, which are considered a bit of a free-for-fall - nobody can claim any one patch of water, but owners of piers do get to claim up to a certain distance from their largest dock.

For the Bivve countries, the only ones currently at war:

Passane: soldiers are provided for by the government in the form of food, board, a general set of weapons/armor (repairs and replacements are covered within reason by the army), and a stipend of money. Military service is required and often serves as general education/prepping for career, as well - someone who cannot fight on the frontlines is expected to become a medic, help manage the supply lines, or assist in administration until their years are over.

Western Dominion: the Dominion is comprised of disparate city-states that have combined their meager militaries in order to protect the Dorvaen Pass as a united front. Each city-state contributes what it can towards the outpost at the Pass, which admittedly does not see much combat since Tine Lumes of Passane retired from the frontlines. Some cities offer less than others, leading to strained tensions.

Vollan: Vollan's small military is highly subsidized by Alleria, who sends food supplies and money which are distributed to the soldiers. Many swap this money with Vollan's local farms for more food, however.

The Federated Union of Alleria: Soldiers live off the land around them in most territories, leading to conflict if the soldiers are not of the local area. However, they do not live in the homes of locals - rather, they live in large camps in the flatlands that make up the Allerian-Passane front. Farmers and hunters whose lands are under stress from occupying soldiers can apply to their territorial government for tax relief or a stipend.

Tashen: Tashen does not have a standing military, but the government has claims to a stockpile of weapons and armor that they would distribute if Passane were to break through Alleria to threaten them. There are many worries that mobilizing a significant chunk of the population to war would deeply cripple Tashen's economy, which depends on the harvesting, processing, and sale of resources to other maritime nations.

The Vaervan Kingdom: Vaervan also lacks a standing military, and has never genuinely had more than a militia. Their reputation is fierce among Bivve and many outsiders believe they would die of some strange and unknowable weapon if they were to march on Vaervan, cementing the idea that they would not even need one.

Callawen Island: there is no military; the Celfoss is a small band of powerful Flames that protects the island. They are cared for materially by the island's government, however.

There are two major areas that come to mind:

First is the northern reaches of Cadava, which are cold and inhospitable to most life. There are creatures, animals, and plants that have adapted to the cold and flourish only in its grip, but most of the sentient races are primed for temperate climates and have not settled it, despite evidence that these existing ecosystems could support a small town. It's also a bit of a miserable place, covered in constant blizzards that occasionally streak violet from Seeplands runoff - why bother colonizing it?

Second is the Maiden's Tangle, the enormous sentient jungle seemingly hellbent on consuming the continent of Moondown. The Tangle is full of life - strange mutated creatures, plants that react swiftly to intruders, and brimming so full of magic that spontaneous sentience occurs here more commonly than anywhere else. There are tribes of sentient races here, too - but these people are not native to the Tangle. Rather, they have become "Tanglelost", obsessed with the jungle and consumed by their desire to become a part of it. They worship the ethereal Maiden, who appears to them in dreams. These tribes do not harvest the Tangle for resources or warp the land to farm or build houses; their relationship with it is somewhat more symbiotic than that.

Ardor: Most Ardor worshippers believe the Ardor died in creating the world, using their Flame (lifeforce) to craft everything. However, their Flames live on and witness all that happens.

Fervor: Many Fervor worshippers believe the Fervor deities have stepped back from creation as a whole to witness if this cycle will be the “perfect” cycle, one that wholly and utterly worships them. Though they will not interfere if the cycle is flawed, they will gift good reincarnations to pious mortals’ next lives.

Mewawa: Mewt Mavet is the sole benefactor of Chellabra and the divine core, a reincarnation of the world’s driving forces. Therefore, the world inherently belongs to him, and will return to him in time.

Forgone Suns, Blistered Moons: The sun and moon shards are not deities, but are ley lines directly tapping into the flow of Magninium and time itself, which allows them to grant powers or visions to warn or encourage individuals. They must be kept untainted from most mortals’ magic to preserve their power, and only those highly attuned to their conceptual wavelength may immerse themselves in their power.

The Star Lovers: The greater gods have forgotten the world in their disgust, leaving behind the mortal remains of their children. Those mortal remains rule the country of Iah-Yah together, where they guide the holy followers to relative safety among Moondown’s many threats.

The Heralds: Considered real, though visions of any are almost always negative. As they generally represent sudden, vicious change - primarily natural disasters - they are seen as omens of bad fortune and one should leave the area if they suspect a sighting. The Heralds in general are not thought of as deities, though, and though small shrines and rituals are dedicated to them, organized worship is not.

Ardor: Positive. The gods blessed this world into beginning and sacrificed their lives so that we may enjoy and indulge in mortal life. We should always express reverence and gratitude towards them for this, and cherish that we exist at all.

Fervor: Positive. The Fervor set the world in motion, and though they can be polarizing figures - someone damning Rhovos or Lethe for a battle lost, for example - ultimately the responsibility lies on mortal shoulders to cherish and align themselves with the Fervor’s energies, to avoid feeding Vallha, the world-eater.

Mewawa: Positive. Mewt Mavet provides for all the denizens that follow him and his Dewclaws, and is an active part of day-to-day Maweth life. His grace is boundless and forgiveness untold. The fact that he cares for every individual so intimately and deeply is a sign of his godhood.

Forgone Suns, Blistered Moons: Neutral. The shards are a blessing, but are not sentient and do not take actions. They are powerful tools that should be respected and admired, but not irrationally blamed or blindly adored.

The Star Lovers: Positive. The star lovers are seen as a tragic tale, and many feel pity or empathy for their plight. Their rebirth is an integral part of the country’s governing and festival cycle, and (at least in recent history) they have all been good people.

The Heralds: Negative. As omens of bad tidings, they are often frowned upon in appearance and stories. As trickster gods, they are especially feared, as many lead individuals astray from their families and countries. Still, it is good to keep a small shrine or two in the village to them, to ward them away with pleasant offerings.

Ardor: Navershin is incredibly popular, as he is the Ardor of mortals and most likely to care for their plight.
Ardor worship, however, stresses the importance of worshipping all the gods - though some favoritism is OK especially if it’s significant to a region or time (worshipping Ceerie or Merse during supernatural events, for example).

Fervor: It is encouraged to choose a member of the Fervor to dedicate oneself to, although there are scholars of the entire pantheon. Most common is Fhalla, who has concepts that are very friendly and easy to indulge, especially revolving around fellowship.
Least common is Lethe, who is generally associated with high contrasts and intensity - love, loss, loyalty, life, liberty, legends, etc. He is also the “end” of the Fervor, representing the last age of a cycle, winter, and water. It is important to pay respect to Lethe especially during his “time”, but actual worship and full dedication to him is very uncommon.
Though, worshipping Vallha - the world-eater - is strictly forbidden and highly blasphemous. It is actively antagonistic to the idea of the cycles and the Fervor religion as a whole, as worship of Vallha causes the world to end, and is usually punishable by death.

Mewawa: Worship of Mewt is encouraged, loved, and happily accepted. Affection for the other religions is seen as childish or naive, especially when there’s a god right there.

Forgone Suns, Blistered Moons: The shards should not (and usually are not) worshipped.

The Star Lovers: They are to be respected and loved, but their mortal reincarnations can be as flawed as actual mortals. It’s common to leave gifts for them during certain holidays, and touching them without permission is expressly forbidden, but it is acceptable to criticize their decisions or advise them.

The Heralds: As they’re largely regional, the Heralds’ worship varies. Most common shrines are dedicated to Veles, the Herald of Death, commonly spotted on Bivve. It is said that the mountains that nestle the Western Dominion are of his creation, meant to shield a great artifact from Passane’s eyes that could stop the war.

Ardor: All the Ardor gods are inherently good-aligned but can act in ways that seem strange or “evil” that are later revealed to be for the greater good or part of a plan.

Fervor: The Fervor gods are all good, despite their plethora of “negative” aspects. These aspects are simply a part of them, devoid of the morality of mortals, and are only ”bad” in context of mortals and their various idiosyncrasies. Vallha, however, is evil incarnate and completely so, as he covets the powers of creation but is only capable of destroying.

Mewawa: Mewt Mavet is a good deity who loves and protects us. (Though most would agree he’s more on the ‘chaotic’ side of things.)

Forgone Suns, Blistered Moons: Assigning morality to the shards is wrong, simple as that. They just are.

The Star Lovers: The lovers can be as flawed as mortals, and as selfish or selfless as mortals have the capacity to be. Their divine heritage, however, enables them to intuit “good” and “right” paths, though usually unrefined.

The Heralds: Somewhat perceived as evil. As known omens/trickster gods, they’re to be avoided, and those who invoke them or make deals with them get what they deserve.

Ardor: Tangible gods, though they died in the world’s creation. Their magic and Flame still flow throughout the world as it slowly returns to Yerxes, the all-being, and are ever-watching. They bestow their Flames upon those blessed by them, to mark them as heralds of their power.

Fervor: Tangible gods, though not accessible to mortals after the start of creation. Vallha is considered to have a very obvious influence, as the source of evil thoughts, urges, and actions.
This corrupting force eventually overtakes the Fervor’s world and enables Vallha to become all-powerful, as he consumes everything and defeats the Fervor one by one. Once they are defeated, however, Vallha is stricken down - as a being of only destruction, when left with nothing to consume, he is powerless.

Mewawa: You can literally come see him during open house hours, 11am-3pm every day.

Forgone Suns, Blistered Moons: The Shards are not gods and should not be considered godly. They are tools and symbols that allow mortals chances to grasp their fates.

The Star Lovers: Tangible, real gods with pieces of divinity in them, though dulled through many mortal reincarnations. One day, they will reclaim their full rights as gods through an elaborate prophecy, and once more will rise to the celestials and repair the suns/moons. They will usher in a new golden era in the world and craft a special eden for their holy followers.

The Heralds: Believed to be more nature spirits or omens than actual gods, though their power isn’t to be sneered on. Paying them proper respects as powerful individuals is important, lest they “punish” a region for failing to do so.

Ardor: Yerxes is not actually dead, though “smiting” him is integral to a cycle’s start. Also, three of the Ardor are dead and nobody knows.

Fervor: This is spoilers, but, Vallha,

Mewawa: Most of the religion is made-up but a lot of it has its basis in actual Ardor lore, since Mewt strangled Mesechev until the latter spilled details to him.

Forgone Suns, Blistered Moons: Every origin story for why the moons and suns shattered is wrong. The stuff about them being ley lines/powerful sources of Magninium isn’t, though it’s a normal feature of most Numbers universes. The whole shards-giving-gifts-or-cursing-the-unworthy is just that people whose magical signatures resonate with the shards get boons, but people who don’t get merc’d.

The Star Lovers: The real spoilers.

The Heralds: Actually like everything about them is true. The only difference is that they’re actually from Evenne and didn’t just spawn out of the earth.

Ardor: Offerings are an integral part of most festivals and every Jarusday it’s expected to give a small gift from the week to the local shrine. For living deities or those blessed by Ardor Flame, direct worship is encouraged - many travel to have Peaches touch their hands or head, and leave him splendid offerings as a sign of piousness. Respect is given at all times to those blessed by Ardor Flame, and many will mutter prayers or bow their heads in the presence of the blessed.
Mewt Mavet is a notable exception to this. Though he holds the Flames of an Ardor god, he is considered a corrupter and a thief, having stolen them for selfish reasons instead of earning them through merit. Thus, he is not worshipped.

Fervor: More common in Fervor is the individual’s personal relationship with their patron, which can be expressed by crafting idols of their gods. Each Fervor god has a different material they prefer, and hand-making a symbol of them to keep is an integral part of worship. Other than that, trying to live according to a patron’s concepts is more important than sacrificing meat or anything.

Mewawa: Mewt does not require anything, for anything given to him is simply returning gifts from whence they came. Instead, to honor him, one should devote their life to his worship and dedication, working to better the country and his power as a whole.

Forgone Suns, Blistered Moons: Gifts are often left for the Clerisy, the individuals who govern Sarens and convene with the shards. Most common are hot meals, toiletries, and clothing, as the Clerisy do not earn money or own anything, having dedicated their lives to the shards and their messages. It’s uncouth to leave offerings for the shards but that doesn’t stop people.

The Star Lovers: Generally, it’s only socially acceptable to leave them things during festivals (and each holiday has different appropriate gifts, like candles and lanterns on New Years’) but many people enjoy leaving them trinkets. Highly valued are handmade crafts, jewelry, and gemstones.

The Heralds: Usually a bit of the years’ harvest in their shrine is enough to ward them away. Leaving them more gifts invites their attention, which spells trouble.

Ardor: The Ardor select inheritors of their Flame, who go on to represent them and do good in the world overall. Though not quite reincarnations of Ardor gods, they are akin to them, and should be respected and loved as the symbol of that particular Ardor god. An example of this is Peaches, who holds both of the Flames of Xharde, Ardor of Time. This is rare, as usually only fragments of their Flames are doled out.

Fervor: The Fervor do not touch creation after setting it in motion, as they wait to see if the mortals will perfect this cycle and be united in love and dedication of the Fervor. However... invoking them conceptually, and living by their concepts is believed to assist mortals. For example, worshipping, following, and acting in the ways of Rhovos is believed to grant great victory during war and battle.

Mewawa: Daily, Mewt expends an eon’s worth of magic to provide food, water, electricity, and resources to his followers. He does this without expectation of thanks or gratitude, seeking only to protect and love his people in tangible ways.

Forgone Suns, Blistered Moons: The shards bless individuals who are attuned to them with more powerful changes and stronger, clearer visions. This does not make individuals ‘favored’ per se, but does mark them as predisposed to being good Clerisy members.

The Star Lovers: Locked in their mortal forms, the lovers are incapable of granting true gifts to their followers. However, when they regain their divinity, they will reward all current and past followers with an eden of unimaginable peace, and a loving world of plenty for foolish outsiders.

The Heralds: Any “gift” from the Heralds is almost certainty a curse. They care not for mortal plights, and simply seek to corrupt or alter peoples’ lives for fun. They particularly enjoy making deals that benefit, in the end, solely them.

Ardor: No Ardor deity would ever curse a mortal, though worship of Aither is a hotly-debated topic. Aither is seen as being struck with misfortune in general, and so symbols or invocations of him are also plagued with bad luck. However, it is oft not seen as his fault and is a part of the tragedy that comprises his identity.

Fervor: The only evil deity is Vallha, the world-eater. His corrupting influence chews at the foundations of the world until it shatters and he consumes it, becoming powerful enough to fight and defeat the Fervor creation deities. Worshipping him expediates this process, as does indulging in evil deeds or actions.

Mewawa: Mewt does not curse people - not even those who worship false gods, in his endless grace.

Forgone Suns, Blistered Moons: The shards can seriously damage people if they are not inherently attuned to their power, causing intense mutations and agony in those unfit for their presence. However, as access to them is heavily restricted, it’s not really their fault if nobodies break in to touch them.

The Star Lovers: The lovers are incapable of cursing anyone in their current state, nor would they when the return to divinity.

The Heralds: Literally all of them, have you been reading?

Ardor: The most rag-tag bunch of them. Ardors with contrasting/complimenting aspects (ex. Navershin of mortals ⤎⤏ Mesechev of celestials) have intimate, close relationships with each other, but otherwise form relations with the others at their leisure.

Fervor: The four gods love and care for one another, though they bicker and argue almost akin to siblings. They do not take slights against each other lightly, and it is uncouth to spit on one of the four while venerating the other. Fhalla particularly frowns upon this.

Mewawa: The other deities are false puppets, but have served the world well in the true core’s absence. They should sacrifice their magic to Mewt to expedite the regaining of his power.

Forgone Suns, Blistered Moons: One day, the shards may return to the suns and the moons. On that day, all will become peaceful.

The Star Lovers: They are explicitly lovers, romantic to the core, and adore one another. Their affection for one another knows no bounds, and they naturally compliment each other, filling in for one another’s weaknesses and creating a larger whole.

The Heralds: Though they are primarily in opposition to one another and throw tantrums when their space is invaded, they are known to occasionally work together for a larger goal - usually worsening the lives of a greater region of people.