Ratskins are a vile species of metahuman, part rat and part man. They live their greedy little lives out in underground superhives, stealing from those aboveground and killing each other over petty squabbles. One of these rats is no happier than when they have more items than their neighbors, thoug there are some who aspire to be more noble than the rest. These noble rats are regularly bullied by the rest, and it isn't unusual for their strongest to be the sole rat allowed to breed with the matriarch.
The Broodlord is the peak of ratskin biology, more rat than man, up to ten feet tall, and ripped as shit. A normal man is nothing more than a snack to a broodlord, and his superior genetics allow for him to maintain leadership above the other ratskin in his hive. This leadership and dominance allows him to maintain sole breeding rights to the matriarch of a hive. It isn't uncommon for another rat to fight to become a challenger for the broodlord, and many have been usurped by the products of natural selection running its course through the rest of the hive. Tests in captivity show that the broodlord's been conditioned via his position to require sexual stimulation every 6 hours, in the absence of a matriarch, this manifests as violent masturbation, and tests using restraints to prevent this shows that the longer an erection persists, the more painful it becomes until the broodlord dies of cardiac arrest.
A hive's matriarch is a massive, bloated female ratskin. It is fully feral and constantly in heat as a byproduct of the rampant breeding needed to create a new hive, very rarely does a hive have multiple matriarchs, but they are universally considered more valuable than the broodlord that inevitably rises to claim sole breeding rights over it. Tests in captivity show that these bloated creatures can hardly move due to the size they've grown to. The severity of the ratskin mutation in a matriarch often directly correlates to the strength of warriors born as a result of a broodlord's seed, with the more genetically pure ratskin matriarchs producing the most potent warriors known to the underhives as compared to the more humanoid ratskin matriarchs.
In the event of a Rook-level infestation, an extermination is ordered and lethal force is required, since they often live in flthy locales, chemical weapons and biological weapons aren't effective enough to eradicate a hive. Recommended teams often include multiple wizards, or a skilled gunslinger and as many wizards as they feel comfortable with bringing.
In the event that a ratskin learns human language, they often slur speech and repeat certain words, namely nouns. A noble ratskin has yet to ascend to being a broodlord, and matriarchs are too mindless to be noble, so the only course of action is to unfortunately erase ratskin underhives once they crop up.