When Standing Howlers can top out at ten feet, their front legs have massive claws designed to rend flesh from bone. Their saliva is acidic, and within it lies the poison to sire werewolves. The first Howlers, near to 100 in number, were cast onto the earth to create chaos. The did this by changing men into beasts (werewolves) so that every one they defeated would tip the scales twice. Howlers were never a creature of the earth, they instead came from the moon; this is the reason for many of their features including a never ending appetite…
When Howlers were created the demon queen that oversaw their conception was with child, her king had ordered that now demons hurt this child. The Howlers, which as a race were quite young misinterpreted this command. Because it was the only child that meant anything to them and the were told not to hurt it they believed that this mercy was extended to all children. Seeing how loyal the howlers were to this command she put them in charge of watching the child, any demon who came unexpected was not given a chance to explain themselves before they were either chased off or eaten. The Demon king was impressed by the howlers ability to turn other demons into wolves to follow in their packs (even if it was a circumstantial situation) and sent the howlers to earth, were they might turn men into demons and aid the demon cause. They were commanded to eat those that they could not turn, and once on earth that meant much livestock and other monsters. When they began to gorge themselves on such generous amounts of meat they grew out of the need to sleep, their hunger provided enough energy to ween themselves off the habit.
Any demons that suffered a Howler’s bite began a canine abomination, loyal to their sire. Any humans who suffered the bite became werewolves, and almost always live out their days alone and insane.
While they suit their task well there are some weaknesses , firstly that they are a very rare beast and that does not often reproduce normally. If a howler and a werewolf were to have a child there would be a 25% chance in creating another howler. Secondly there are not immortal, difficult to kill but not impossible. Thirdly they are still loyal to the command to not injure a child, so much so that they become stunned and often howl mournfully if they must hear one crying.