Hotheads

We had been walking across the barren frozen north for nearly a week in search of the great Ice Pillar when we first began to come across the pits. While all around us the white snow glistened and reflected the sun's rays we began to pass a series of strange holes that looked like they had been bored into the snow and ice. At first these curiosities piqued our interest, but we could find no explanation for them after inspection and our mission could not stand delay. Upon seeing steam come out a a nearby hole, we concluded they could be caused by thermal vents in the earth and went closer to investigate and perhaps warm our numb fingers. With a loud crunch and a scream, my faithful squire Furtham disappeared before my very eyes. I heard screams coming from below and saw that he was somehow trapped with his arms above his head inside a ten foot deep hole in ice beneath my feet. Quite remarkably the hole was so narrow and slippery that he could not climb out of it or even move hardly at all. I quickly scrambled over to him, lay on my stomach and reached down into the pit to grab his arm. Then, the ice shelf beneath me collapsed.

-excerpt from the journal of Sir Orin of Veda, Knight of the Chalice, describing his discovery of the Hotheads.
Full Description
Hotheads are brown furry mammals that look vaguely like bagers and which can grow to roughly two feet in length. Unlike badgers, Hotheads have no eyes and instead rely on their large floppy rabbit ears to track prey by listening to vibrations, as they can hear the footsteps or breathing of another animal from tens of yards away. When they capture their prey, they usually press their sensitive ears tightly against their heads to prevent being damaged by the relative amount of noise of a squealing victim. Once this occurs, they rely on their fine senses of touch and smell to last until the prey quiets down again.
The most remarkable feature of a hothead is a hard plate on top of their head. This plate is an absolute marvel of science and is what gives Hotheads their names. The hard shell is made out of a thermoelectric material which converts normal electrical nerve impulses to heat. Meanwhile, the surrounding tissue is very rich in blood vessels, which carry heat away from the plate and to the entire top of the animal's head. The hotheads can control when the plate is active and can quickly tunnel through ice with these plates. In areas where there is soil underneath the ice, the hotheads use their claws and teeth to dig through the dirt.

It takes a lot of energy (food) to maintain their high body temperature in the frozen lands, and because hotheads are small and not particularly dangerous in open combat they are sneaky fighters. They create and live in extensive tunnel networks under the ice, and will bore holes almost all the way to the surface. The hotheads will create hundreds of these thin ice traps and wait for foraging animals to fall in. The hotheads try to make their pits such that animals like penguins, moose, bear (whatever animal lives in their biome in your world) will be immobilized. The hotheads will check these traps periodically and receive an effortless frozen dinner.
Hotheads will also occasionally track prey and try to capture them on the spot, especially if they are very hungry. They have learned that humans often rescue each other, and thus will set multiple traps or begin to feed on a victim's ankles before his allies can pull him out. Only if absolutely necessary will they engage in 'fair' combat, using their numbers (they also stay in packs) and their sharp teeth and front claws to injure prey/attackers.
Hotheads are very social creatures, and will playfully chase each other around in circles, nip at another's floppy ears and even melt the ice out from under a sibling as a sign of playful affection. The young are very curious and may pop their heads out of their holes like prairie dogs, although their elders vibrate angrily at this because it may warn away prey. Hotheads are rather cowardly animals and will not choose to fight if they have other options (running away, quickly boring a tunnel too small to be followed through, or leaving a cloud of obscuring steam behind from a section of rapidly sublimed ice). They are, however, very loyal to their pack. If one Hothead is in trouble the others will endeavor to trap or distract its tormentors to save their friend.
Additional Information
1) If hotheads are unprepared loud noises can cause extreme pain, and they will retreat. Because of this many native peoples refuse to travel the north without a large collection or drums and cowbells to keep the hotheads away.
2) Because of their cute and playful nature hotheads could make a fun pet or circus attraction if they could be domesticated.
3) Their thermoelectric plate is nonmagical in nature, but could serve as an ingredient for any number of heat or electricity/lightning based magic items.
4) It is rumored that a variant of hothead exists, very similar in nature, except they can not heat up their headplate. These nameless creatures resulted when the ice shelf receded, leaving no use for the hot head plate, which wasted resources. Over time the animals lost the ability to heat their headplate, and it now serves merely as a protective covering. Despite this seemingly major change, these animals still act in much the same way, digging holes in dirt with their claws (which have grown larger and sharper).
5) The hotheads have an active partnership with the Bulral and a strong hatred of the skets, two creatures linked to this article. For brevity, I included that in the other posts only.
Inspiration
Credit for inspiration goes to Discover Magazine, April 1, 1995 Prank Article.