Magnatherium

The «Magnatherium» (マグナテリウム) is a rare monster, found in the Bear Forest on the 4th Floor of Aincrad in Sword Art Online, which drops high-quality items needed for the Shipwright of Yore quest. The bear spawns near a tree that has characteristic four-pronged claw marks on its trunk.

Appearance
The Magnatherium has gray hair, with each hair as thick as a needle, two red eyes that gleam in the dark, fierce fangs poking from its massive jaws, dagger-like claws protruding from its limbs, which are as burly as logs, a barrel-size but still short and bear-like tail, and black, sharp, gleaming horns on its forehead. The beast is about eight metres tall when it stands on two legs and nearly four metres tall at the shoulder when it stands on all four.

Attack Patterns
When the Magnatherium stands up vertically, sucks in air, and a red light flickers deep within its throat, it begins to use a fire breath attack. This attack can be avoided by running between the bear's legs to reach its backside, which is out of range of the flames, or by jumping into a spring. However, the same spring cannot be used indefinitely, as a single fire breath attack produces enough heat to increase the temperature of a near-freezing spring to that of a hot bath. If there is a long enough distance to its targets, the bear begins advancing on all fours, suddenly lowers its horns and begins charging, following its prey until it hits either a large tree or its targets. It stops moving for about twenty-five seconds after a fire breath attack, and for about fifty seconds after a charge attack. At close range, the bear uses its dagger-like claws to attack the player.

Barcarolle of Froth
Having accepted the Shipwright of Yore quest, Kirito and Asuna came to the Bear Forest to gather bear fat for one of the quest's requirements. However, Asuna was determined to acquire the high-quality version of the bear fat; thus, they began looking for the territorial claw markings of the king of the bears. Eventually, Kirito noticed these markings on one of the trees. Just as the two of them noticed that the markings were eight metres above the ground, the Magnatherium appeared. When the bear stood up vertically, Kirito and Asuna retreated behind a large tree, anticipating a charge attack. However, the bear was actually planning to use a fire breath attack. In order to avoid the flames, Kirito and Asuna jumped backwards into a small but deep spring. After the attack, Kirito suggested to retreat for the time being, but was convinced by Asuna to at least collect more intel on the monster before doing so.

At that moment, the Magnatherium began charging towards Kirito and Asuna and easily crushed the large, old tree that they had hidden behind; however, the collision stopped the bear's attack and temporarily rendered it immobile. While Kirito was considering their next course of action, he noticed that the fallen tree trunk had not completely disappeared, and hence was likely to be a game object that could be collected. He asked Asuna to investigate while he lured the bear away. Once he and the Magnatherium were a safe distance from Asuna, Kirito attempted to counter the bear's claw attack with «Slant», and managed to barely remain standing despite the impact having smashed him into a tree.

When Kirito stepped forward, the bear stood up to use another fire breath attack. However, Kirito ran forward through its legs to avoid the flames. Once he was behind the bear, and while it was still occupied with its attack, Kirito used «Sonic Leap» to attack its tail, which was about three metres above the ground. At that moment, Asuna returned and informed him about the log that she had investigated. Kirito suspected that it would be required for a later part of the quest, and thus, in order to obtain more logs, the two of them repeatedly guided the bear to charge at large trees.

When the pair no longer had free inventory space for more logs, Kirito suggested retreating to town, but Asuna reminded him that they still needed bear fat for the quest, and that she would not settle for ordinary bear fat. Thus, they began to actively attack the bear, which still had ninety percent of its hit points remaining. Kirito decided that he should use Sword Skills to deflect the bear's attacks, after which Asuna would cautiously switch in for a single attack. After a fifty-minute battle, the pair finally managed to defeat the Magnatherium, and received various high-quality drop items.

Trivia

 * The word "magna" in Magnatherium is derived from the Latin word "magnus" (great), while "therium" is derived from the Greek word "therion" (beast).
 * One of the Magnatherium's weaknesses is its tail.
 * The Magnatherium's charge attacks can be used to chop down large trees to acquire Noblewood Cores, a high-quality version of an item required for the Shipwright of Yore quest, without needing the Lumber skill.