Bilaruk (5e Creature)

Gargantuan beast, unaligned

Armor Class 14 (natural armor)
Hit Points 280 (16d20 + 112)
Speed 0 ft., swim 25 ft.

Saving Throws Con +12
Skills Perception +6
Senses passive Perception 16
Languages —
Challenge 15 (13,000 XP)

Charge. If the bilaruk moves at least 20 feet straight toward a creature and then hits it with a ram attack on the same turn, that target must succeed on a DC 18 Strength saving throw or be knocked prone. If the target is prone, the bilaruk can make one tail attack against it as a bonus action.

Hold Breath. The bilaruk can hold its breath for 90 minutes.

Keen Smell. The bilaruk has advantage on Wisdom (Perception) checks that rely on smell.

Reckless. At the start of its turn, the bilaruk can gain advantage on all melee weapon attack rolls it makes during that turn, but attack rolls against it have advantage until the start of its next turn.

Relentless (Recharges after a Short or Long Rest). If the bilaruk takes 24 damage or less that would reduce it to 0 hit points, it is reduced to 1 hit point instead.

Thick Skin. If a melee attack deals less than 20 damage to the bilaruk, the damage is reduced to 5.

Like modern mammals on Earth after the End Cretaceous extinction, multituberculates^[1] presented their own contender for aquatic niches after the end of the Dynastic Extinction 15 million years ago. Extinction events on this scale often are a sort of ecological stepping down of the new guard, with a wide range of more adaptable survivors experiencing abundant adaptive radiation before establishing a new statis que and the oceans are a particularly common arena for such evolutionary battle grounds. Both on earth and Kaimere, mammals have taken to these niches multiple times and multituberculates have presented at least two aquatic lineages in the last 15 million years. One of these multituberculates is the also the largest of both Earth and Kaimere, with cows often weighing 35 tons and bulls routinely doubling the mass. These immense, unusual giants, with a shear-like premolar, long tusked incisors, baleen-analogue on the roofs of their mouths, and a venomous spur on the hind flipper in bulls, are known to the Assembly as leviathan (Thalassochoerus leviathan "Leviathan sea pig"), and the Kenterim who most readily encounter them call them bilaruk.
Whale of a Tale. As stated above, the bilaruk can trace its ancestry to shortly after the Dynastic Extinction, to a clade of multituberculates called plektocetids ("spur whales") which evolved in Kairul's interior seaway. This equatorial inland sea was ruled by a host of plesiosaurs and metriorhynchids^[2] who perished along with the rest of the great sea monsters during the Dynastic Extinction, opening the door for new clades like the plektocetids to evolve. Like true cetaceans, plektocetids were ancestrally semi-aquatic predators not unlike crocodiles, who took to open water once opportunities presented themselves and quickly transitioned form otter-like paddlers to tail propelled swimmers, from there diversifying in the inner seaway of the eastern continent, from dolphin-like fish specialists, durophagous shell-crackers like the unrelated sea beavers, and a variety of omnivores that sifted sediments for water plants and benthic invertebrates.
The latter lineage is where Thalassochoerus evolved, with several species recorded in the Kairulen seaway today and at some point, perhaps descended from a few small pods, the ancestors of T. leviathan spread out from there and likly followed the eastbound current to the Great Khalin Sea or western Arvel and from there throughout the Known World. As these individuals form a single species today and there is evidence in both genetic and fossil studies of a bottleneck^[3] within the past million years, this likely occurred quite recently during one of the Pleistocene harvests when seasonality spiked and the resulting toll on the oceans opened up space in the sea, though some have suggested they may have come much earlier during the aftermath of the End Anchored Period Extinction when the sea levels lowered and caused great biotic turnover.
Success and Abundance. Whatever their origins, bilaruk are extremely successful and widespread in the warm waters of the Trakaiam Sea and beyond. Despite this success and what their appearance outwardly may suggest, they have very little blubber, instead mostly having extremely thick skin, and don't take terribly well to cold, thus making them unable to handle open water for long though they are better in this regard than animals like the desmostylians,^[4] sirenians, and kurajaku. This makes them not terribly common in the Great Khalin Sea, visitation being only really viable in the summer during which they feed on the abundant kelp and benthic fauna, but their tolerance of heat allows them to winter in the warmest waters Trakaiam Sea where few cetaceans over a ton can endure with any form of comfort.
Bilaruk can afford to be massive thanks to bulk feeding on a very diverse diet and a massive gut that is more than capable of processing a lot of food. Their base diet consists of seagrass, which they uproot with their massive tusks and draw back into the mouth with a barbed tongue to be shredded by the blade-like premolars. The above mentioned baleen analogue is thought to be derived from highly keratinized skin and helps to filter out sediment from the seagrass, their roots, and benthic fauna hiding within. In addition to their tusks, this feeding method of rootling through the sediment is how they got the scientific name "sea pig." This feeding method is highly destabilizing to patches of sea grass compared to other seagrass grazers, but bilaruk do not have exclusively destructive influences on their environment: the seeds of seagrass can typically endure the bilaruk's stomach and their dung forms makes excellent fertilizer. If no seagrass takes root in that space however, than that space is likely to be the beginnings of a new coral reef.
Because of their fairly destructive method of feeding, pods cannot grow too large, comprising almost exclusively comprising 1-12 cows and their calves. Calves are born 3 meters long and if it's a female is likely to reach a max of fifteen meters, as cows do not grow much after sexual maturity, weighing between 30-35 tons. Bulls however continue growing after that and by ten years of age most plateau at a tremendous 22 meters, though some are even larger, and often double the mass of cows. Bulls also have thicker hide in their trunks and are more robust overall. Unlike cows, bulls are solitary though occasionally youngsters will form bachelor pods and follow an adult bull around. Though bilaruk do come from a pouched lineage, multituberculate pouches are not like those of marsupials, only used for carrying the young, and bilaruk have lost them entirely as their young are born able to swim.
While it is said that bulls have larger tusks than cows, the difference if fairly minimal as both sexes use them on a daily basis for feeding. They are also used in combat as both bulls and cows are quite violent with members of their own sex and their courtship also involves lots of biting. In fights for mates, bulls also use their venomous spurs to effectively sterilize their rival for a few hours due to swelling of the pelvic region, a tactic they also use to on cows after mating to prevent other males from doing so. While experienced bulls know to inject the spurs above the pelvic region to inhibit defecation, younger bulls may struggle with this, though as older bulls usually are the ones mating anyway due to their size and combat experience this rarely occurs.
Prey and Predator Being free-swimmers, bilaruk prefer to feed in much deeper zones than the more abundant sloths and desmostylians^[5] and their size makes them safer than sirenians in the same zones. In fact, the bulk of bilaruk means they often have entourages of sirenians following them for protection from sharks and other threats. Though occasionally they have to keep an eye out, seagrass rarely grows in waters deep enough for an adult megalodon or motomazor so the leviathans are often safe. There is however, a predator that does dwell here, and is easily large enough to take these behemoth multituburculates, and indeed sometimes specialize for them almost exclusively: the kurajaku.
These megaraptorans have very thick skin, dense bones, barely any body fat, and air sacs which compress when they dive, so can’t reliably swim in open water. However, they can run fast along the substrate due to negative buoyancy and powerful caudifemoralis muscles connecting short and laterally-compressed drag-reducing legs and broad tails. Oiled feathers provide camouflage, enabling them to get close to their prey. Though bilaruk have decent eyesight, they often rely upon an extremely potent sense of smell to detect food and predators as they inhale. Kurajaku also have very keen senses of smell and sight, often approaching downwind so they don’t smell them when they come up for air.
However, bilaruk are far from defenseless: their tusks extend up to two meters from the roots, perfect for driving through kurajaku's thick skin, and the barnacled rostrum can deal quite vicious, if usually superficial wounds. This is all powered by massive muscles, allowing them to pivot and strike with tremendous force, and their spurs provide excellent backup weapons. However, an experienced kurajaku can run alongside the bilaruk while feeding and if they land a bite on the back of the neck, keeping the belly facing away from them, the leviathan is basically helpless as the megaraptoran plunges its meter long claws into its chest for the killing blow. Even though both are muscular and the kurajaku's air sacs are compressed, the theropod wins in a contest of endurance almost every time and they're so dense that they can sit still and effectively let the struggling sea monster drown itself in the effort to escape.
This is where the pods of bilaruk are quite handy, as while the megaraptoran is unmatched in a brawl, they can be vulnerable in a grapple: as long as the pod doesn't scatter, they can land debilitating bites on the kurajaku's back half, where its stiff torso would make it difficult for them to turn to retaliate. While not as intelligent as true whales, the bilaruk is among the forerunners in multituberculate intelligence in Kaimere and this coordinated defense has served them well. Even so however, bilaruk can make up a majority of some kurajaku individuals' diet, with an experienced megaraptoran able to reliably get a quick kill before dragging the body to shallow water to feed in peace. Such individuals also know bulls are easier to kill in the breeding season, when they are tired and beaten from constant fighting and mating and, because they are competition for mates, bulls are unlikely to come to the rescue of one another. However, bachelor groups outside the breeding season are much more likely to defend each other and paired with their success as seagrass grazers and the respect they have among the people's of Kaimere as a pinnicale of virility, bilaruk are successful without a doubt and here in the Inland Sea to stay.