Renzhuyo (5e Creature)

Large beast, unaligned

Armor Class 13 (natural armor)
Hit Points 47 (5d10 + 20)
Speed 15 ft., swim 25 ft.

Saving Throws Con +7
Skills Perception +4, Stealth +6
Senses passive Perception 14
Languages —
Challenge 5 (1,800 XP)

Ambusher. The renzhuyo has advantage on attack rolls against any creature it has surprised.

Hold Breath. The renzhuyo can hold its breath for 20 minutes.

Pounce If the renzhuyo uses at least 10 feet of its walking speed or 20 feet of its swim speed to move straight toward a creature and then hits it with a claw attack on the same turn, that target must succeed on a DC 14 Strength saving throw or be knocked prone. If the target is prone, the renzhuyo can make one bite attack against it as a bonus action.

Wetland Camouflage. The renzhuyo has advantage on Dexterity (Stealth) checks made in swamp or underwater environments.

The crown jewel of the Crescent and the breadbasket of the Cha'Khati Empire, the Seridic Wetlands is a vast culmination of a thousand rivers. Though the mountains and highland sources have swift flowing streams, the majority of the wetland is lazy rivers pocked with often quite deep lakes. Herds of hippopotamus, rhinoceros, water buffalo, thescelosaur, oliphaunt, and ceratopsian dinosaurs, along with crocodiles and three great theropods in the form of the ba'khar, zentaur, and kurajaku, all carve channels through the rivers which the people use to navigate and hunt the bountiful glut of fish, both massive and abundant. Though there are many dangers in this habitat, one name is spoken among the Serid with particular unease: renzhuyo (Temnodon tigripotamus "Cutting toothed river tiger"), "Death crawls from the river."
The Meek Inherit the River. The Assembly long classified the renzhuyo as an unusual, perhaps basal, seal, but the Great Library put them in the same category as the mud bear and dire otter of Kaishel due to their similar molars. After the two came together for a more comprehensive study that included looking at fossils from Earth, it was discovered that the renzhuyo, mud bear, dire otter, and related animals are all members of the order Hyaenodonta,^[1] a group of placental mammals best described as carnivorans before Carnivora.^[2] One of the distinguishing features of this clade is their teeth, which are adapted to cut not crush, despite the name that compares them to hyenas, meaning that, as confirmed by Kaimeran clades, they were less versatile in their diet and strictly carnivores. Although the clade is known on Earth for robust apex predators, such as Hyaenodon itself, these hyaenodonts brought to Kaimere during the Oligocene Harvest failed to establish themselves amidst the competition. Instead it was smaller hyaenadonts similar to to Apterodon^[3] that found success.
Some apterodontids filled a similar niche to otters, from which the Kaishellan clade that evolved into the dire otter evolved and even became secondarily terrestrial, leading to the mud bear and water panther. That clade did have small generalists, but otters introduced to Kaimere later outcompeted them, although hyaenodonts excluded otters from macropredatory niches. Another clade of apterodontids became robust wetland predators, the largest of which is still found in Kairul today and punts along the bottom of rivers like a hippopotamus. Another clade, Phocopotamidae ("River seals"), derived into creatures similar to earless seals in shape but with long, flexible, clawed forelimbs. It is from this clade the renzhuyo is descended.
Death Crawls from the River. The river seal hyaenodonts proved to be quite successful even after the Dynastic Extinction, with several genera still found in Kairul today. One genus is the macropredatory Temnodon, of which the renzhuyo is included, and giant 7 meter species are well recorded. However, it was a more conservative 2 meter species that made its way to the Known World, pursuing fish and small mammals along the coasts, even with their preference of freshwater conditions to saltwater which is why they found success in the Seridic Wetlands. As their specializations for agility over speed mean they don't do terribly well in open water, the lazy Seridic rivers proved the perfect habitat for the renzhuyo, so much so that their abundance may deceive one into believing them to be an ancient and stable anchor in the region. Yet the fossil evidence really does suggest they are a recent addition to the Seridic cast. The reasons they haven't spread beyond the Crescent is suggested to be a poor tolerance to cold water caused by a deceptive lack of any fat deposits, meaning they are, in the Known World, only found in the Seridic Wetlands with a small population in the western rivers of the northern Crescent.
Although the rear half of a renzhuyo resembles a seal, particularly the hindlimbs adapted for the same lateral stroke swimming method as phocid seals,^[4] the forelimbs remain long, clawed, and actually increased in flexibility to help them navigate wetland terrain and vegetation. Despite how recent they are to the ecosystem, renzhuyo are the most common predator in their size and niche in the Seridic Wetlands, outnumbered only by crocodiles which can get just as large on a less demanding diet. Though their ancestor was smaller, renzhuyo themselves are large and formidable, with females reaching 3 meters in length and weighing half a ton while males are a meter longer and double the mass. They are versatile predators that take a wide variety of prey, from large fish, crocodiles, and deer, to even juvenile hippos, and large thescelasaur drakes. Though principally an ambush predator, their agility paired with short bursts of impressive speed allows them to not only catch and overpower a wide variety of prey but also keep out of the claws and jaws of larger crocodiles, kurajaku, and ba'khar. Part of the reason renzhuyo are so feared by the Seride is that, while not principally such, they can very easily take to maneating due to an already flexible diet.
Male renzhuyo are solitary animals that mark their territories with resonate, throaty screams, while females are more social and have territories that intersect with related females and often have several cubs in varying growth stages. Females will often look after or at least tolerate the presence of related cubs while their mother forages, a behavior likely partially driven by the renzhuyo's slow growth. Like all hyaenadonts, renzhuyo teeth rupture at the age of 3-4 and their growth slows dramatically at this time. While subadults can survive on their own and aren't entirely reliant on their mother's for food, it is beneficial for them to have a steady source of food while their teeth are in development. This reproductive strategy is thought to be why big cats common in other wetlands, like the red panther and tiger, are quite rare in the Seridic Wetlands, although the faster growth and larger litters of big cats may be an advantage in other regions. Until more detailed study of the Seridic Wetlands can be made, much of that remains conjecture. What is clear is that renzhuyo are iconic predators of the Seridic Wetlands, both feared and respected by the Seride, and in such a competitive habitat, it's little wonder they are so ferocious.