Mooncalves

Mooncalves are otherworldly monstrosities from the Far Realm that haunt the spaces between the worlds. Following some little-understood cycle, they enter the world for a period of weeks, lairing atop desolate mountains and lonely hills, often near settlements where food is abundant.
Ringed by mountains and dotted with hills, the Nentir Vale remains a favorite location for the predatory mooncalves. Sages of Nerath used to predict with great accuracy the arrival of these horrific beasts, but much of that knowledge has been lost since Nerath’s fall. A mooncalf combines the body of an immense cephalopod with the wings of a bat. It has six short tentacles that it uses to grab prey and two long, flailing tentacles that it uses to attack at a distance. The creature’s beaklike mouth is located where the tentacles meet the base of its body.
Visitors from Beyond: Roughly every eight years, a small group of 2–5 mooncalves, called a grasp, preys upon a localized area (a few square miles) for a single lunar cycle before returning to the place they came from. Mooncalves typically hunt at night, resting during the daylight hours. Although not choosy about prey, mooncalves particularly enjoy the flesh of humanoids and cattle, making them a true menace to villages and towns. A grasp of feasting mooncalves can devour an entire settlement and its livestock in a matter of weeks. Hammerfast once fell prey to a solitary mooncalf of formidable size, and it took the combined efforts of the town militia and a group of adventurers to slay the beast. A small dwarven fort in the foothills of the Dawnforge Mountains between Hammerfast and Harkenwold didn’t fare as well; a grasp of mooncalves made nightly visits until the survivors abandoned the outpost. Of all the places in the Nentir Vale that attract such creatures, Thunderspire Mountain might be the mooncalves’ favorite haunt. The creatures are drawn to the perpetual storm that engulfs the mountain’s peak, and from stormwracked promontories they descend upon passing trade caravans without warning and without mercy.
The most popular account of a mooncalf attack in the Nentir Vale is still recounted in the taverns of Fallcrest and Winterhaven, even though the event occurred almost a generation ago. Two human hunters sleeping on the shore of Lake Wintermist in early summer were set upon by a hungry manticore. One of the hunters was quickly slain, pierced through the heart by one of  the manticore’s tail spikes. As the other hunter fought for his life, a tentacle reached down from the night sky, wrapped itself around the manticore, and pulled the creature up into darkness. The manticore’s roars were silenced quickly. Hiding in the bushes, the surviving hunter saw a monstrous shape silhouetted against the full moon—a bat-winged horror flying off with the dead manticore in its clutches.
Mooncalves tend to lair in high places and often find themselves at odds with chimeras, griffons, manticores, perytons, and other mountain-dwelling predators. Mooncalves understand Deep Speech but do not speak it. They can communicate telepathically with each other and with any other creature within 100 feet. However, only creatures that understand Deep Speech can fathom a mooncalf’s thoughts, which tend to be primal and focused on killing and eating.
Relentless Hunters: Mooncalves impose their will upon prey, using lures to draw enemies within reach of their long tentacles. In melee, they like to crush enemies with their tentacles or drag foes to their slavering beaks. Mooncalves also have the ability to conjure small but intense thunderstorms, which they use to incite panic among their enemies.
When a mooncalf becomes separated from its kin, it either begins hunting alone, eventually becoming a mooncalf rogue, or it allies itself with another creature it deems worthy. Evil wizards who draw magic or inspiration from the Far Realm occasionally forge bonds with solitary mooncalves and even ride them as mounts