Incendium is a fire-serpent/demon. It is not a true serpent because it has two front legs that it uses to burn its prey. It has the head and body of a snake, and its eyes cast a spell that causes confusion and hallucinations.
In Hyrule, myths are told about Incendium. These myths are told through oral traditions and only a few have been written down, so there are many and even more variations to those myths.
To defeat Incendium, you must cause a landslide by eroding the rocks surrounding the monster with water. The monster will then be trapped and will die from lack of oxygen.