"It's rumored to control all of the elements, but most, if not all, records of its existence have been burned."
Alatreon is elementally unstable, possessing control over the Dragon, Fire, Ice, Thunder and Water elements. When transitioning into Flight Mode, Alatreon will fly high into the air and can rain down ice crystals. Some ice crystals fall on random spots while others may target certain players. Now it is able to call down Lightning to strike the hunter, much like the White Fatalis, both on the ground or in the air. When it is about to perform this attack, its horns will crackle with lightning, damaging anything in contact with it. Its colors are also more pronounced and shift to reflect its various elemental modes.
Alatreons are very territorial. This may be the reason why no other monsters live in the Sacred Land. Alatreon might attack most of its prey from the air, giving it an advantage over most other monsters. It also is very aggressive towards flying objects, mainly airships.
Alatreon are fought in the Sacred Land, an area within the Volcano. They presumably have access to any point within the Volcano when they hunt for food, and they may even venture beyond the volcano at times. They're also seen in the Ingle Isle. In the New World they have been sighted in the Secluded Valley, given the absence of its original resident. Interestingly, individuals found in the New World appear distinctly smaller than the specimens found in the Sacred Land.