Mivilorn

A mivilorn was a breed of massive dog-like magical beast native to the planes that was a favorite war-mount of a number of demons.

Description
Like a cross between a dog and an especially large elephant, a mivilorn had a massive body and a blocky build. A normal specimen was almost high at the shoulder,  from nose to tail, and more than  in weight. Its hide was dark gray and hairless, with a wrinkled and tough appearance, while those in the wild were usually encrusted with mud. While its big feet were like a lion's paws, its great weight meant they were incapable of clawing in combat. Nevertheless, their structure made the mivilorn startlingly agile for its size and weight.

Yet the mivilorn's most distinctive feature was its huge and oversized head, similar to a mastiff's but of the same width as its body. It had prominent loose skin hanging at its jowls, which helped it to open its jaws to a shocking degree— from upper to lower jaws and wide at its maximum—and so swallow multiple smaller creatures whole. In its maw, it had large, jutting and jagged teeth to crush and puncture its victims. Worse, within the jowls were glands that produced a powerful digestive acid, with much of the digestion process taking place within the mouth. This acid dripped from the gums and teeth, and leaked out even when the mivilorn had its mouth closed.

Behavior
Wild mivilorns were highly aggressive and spent their time hunting for food, taking prey the size of humans or bigger. They flourished when fending for themselves in this way.

They understood simple commands made in Abyssal, but could not speak.

Abilities
To pre-digest, a mivilorn could vomit its acid over a distance of and that much wide, badly burning all those caught in the area. It could do this thrice a day.

A creature of chaos, the mivilorn's bite could overcome the resistance of beings of law, but it was not vulnerable to lawfully aligned weapons itself. It was also resistant to spells.

A mivilorn could see by darkvision and low-light vision and could also track by scent, and generally had alert senses.

Combat
When engaging at a distance, a mivilorn would instinctively charge in and stretch wide its horrible mouth to scoop up its opponent and swallow it whole, all in one shocking assault, if they were not quick enough to evade. Otherwise, it would try to bite and grab hold, and then swallow. It always bit with powerful force.

Either way, it could seize two human-sized creatures at once, or one ogre-sized creature. Both would be chomped, and then trapped in its acid-filled mouth. Thereafter, they were relentlessly masticated and slowly digested. Should the victims somehow survive and succeed in injuring the mivilorn from within its mouth (which was only vulnerable to bludgeoning weapons), it would spit them out. Otherwise, after about 20 seconds, the mivilorn would spit its victim out anyway, just to see if it was still alive. If it was, then it would try to grab and swallow them again.

Ecology
Mivilorns normally wandered the Windswept Depths of Pandemonium in the Great Wheel cosmology or Fury's Heart in the World Tree cosmology.

They could be found alone or in herds of six to thirty members.

Usage
Owing to their size, power, and aggression, mivilorns were valued as war mounts, at least by those brave, talented, and reckless enough to dare attempt riding one. They were often used as such by demons, who would subdue them, train them, and force them into their armies, and jealously guard the secret of just how they were able to do so. If not magically controlled, the mivilorn would attack its trainer or rider as soon as they made any failure in the task, to the exclusion of all other enemies.

Such demon war mounts were elite specimens that were fully creatures of chaos. They were inured to the battlefield, and used their attacks and abilities only when directed by their riders. They were dressed in splint mail barding. They were often taken to fight in the Blood War at the Blood Rift.