"Bears are aggressive in all instances. From their bodily structure, we can assume they are carnivorous. They can climb as well as a cat, smell as well as a dog, and swim as well as a fish. They can run nearly as fast as a horse. They have skin as thick as armour. They are perfect killing machines."
"Mages can fell a squadron of soldiers just by summoning a single one of these beasts. They can keep fighting long after it seems they have died. The best option when fighting one is to trick it into a pit, and then fire arrows until it dies. Attempting to engage one will almost certainly end in the demise of the fool who dared stand and face one. And worst of all, where there are bears, druids will almost certainly follow."
"Ware the bear."
-Scholar Idvonictis, from the academy of the undying
This is the closest you'll come to seeing an actual bear.
Bears have the odd habit of not existing. Not properly anyway, like any decent creature should.
Bears do not exist in nature. They are a purely created species. Nobody knows why they can be summoned, especially since all other summoned animals are simply disguised otherworldly beings, such as fae and fiends. But bears seem content to be purely natural animals, but not exist in nature.
More terrifying still, is that bears look alien. They are a strange mish-mash of beings, and many have theorized that they bring a hint of madness from wherever they came from. Any who look upon them must steel their minds, or go mad from the pure sight of a bear. Many victims report seeing a bear in their dreams, hunting them, looking to kill them even after it's death...
Divination spells looking for some sign of where bears came from, or if they ever really existed, turn up nothing. Painstaking, week-long rituals conducted to find the first person who summoned one fail. Even attempts to follow a bear back to wherever they go once they are de-summoned result in the magic-user being painfully shunted back to reality.
People have long-since given up on trying to decipher the mystery of bears. Only some fanatical druids, who take their shape in an attempt to learn more about them, still try. And even those druids generally end up mauled when one of their summoned creatures turn against them.
This does not mean bears are not feared as much as they are in our world. On the contrary, they are more terrifying. People do not guard their backs while taking a stroll through the woods. They check their attic to make sure a bear isn't going to come crashing through the ceiling, like a furry meteor of teeth and claws.
The stuff of nightmares.
Bears are more than a natural threat, like cougars or wolves or other manageable threats that have cautionary tales about them. Stories about bears are more like ghost stories.
They are every child's bad dream, the fear of every soldier, and why hunters carry an extra sword, just in case. They are the lurking eyes in the dark, the madness that lies out of sight behind the tree, and the fear that lurks in the hearts of men.
They are furry, berry-eating bogeymen.
Up north, where ice flats stretch for miles, whales swim in frozen waters, and glaciers blot out the sun, live the Nosi.
They look similar to bears, but somehow elongated. Changed, warped, and stretched into a form better suited for their environment. They do not share many key bear traits, such as their somehow alien look, and they cannot be summoned. But most fear them as much as bears, for one simple reason: Nosi are big.
Like, really, really big.
When a Nosi walks, the ice cracks under it's weight. Where a Nosi sleeps, birds rest in it's warm fur like fleas. Where a Nosi hunts, all living beings flee.
Nosi hunt whales. They break open the ice, smashing through it with their immense front paws, and break through to the unsuspecting whales below. If you've ever seen a regular bear hunting salmon, that's kinda what it looks like. They leave some of the fat, which coats them in a layer of protective coating. A Nosi lit on fire will burn, but the fires will not hurt it for a while, although it will need to put them out.
Nosi have also made some sort of deal with ravens. The birds get a warm place to live, and easy picking from carcasses. In exchange, the Nosi gets eyes all over it's body, and an extra layer of defense in case someone tries to climb up onto them.
Many northern Utakita tribes worship them as gods. They lope along in their wake, following the enormous tracks the Nosi leaves in the ice and snow. Each tribe has a group of designated 'fur-cutters,' called 'skinskutu' in their native langauge. These people sneak up on the Nosi as it sleeps, and harvest it's fur. They also gather fur the Nosi drops. They are easily identifiable by their enormous, fur-filled backpacks and their clothing being purely white on the inside. The backpacks double as sleeping-bags if the cutter gets lost or stranded for a night or more out in the open wastes. In addition, the smell of it's own fur will confuse an angry Nosi, sometimes leading them to wander off.
Not that this often works. But when a bear the size of a mountain comes bearing down at you, a small assurance is better than none. And beside a Nosi, you will feel very, very small.
A Nosi held captive by magic, ready for war.
Yes, this means you can replicate the movie 'birds'
with giant polar bears as mobile fortresses. Don't
get too excited.