This, ladies and gentlemen, is Melalo, described in the Book of Creatures website as "the oldest and most feared of Ana's children." His name literally means "filthy", "dirty" or even "obscene". This guy is said to project "anger, rage, cruelty, sadism, frenzy, rape, and insanity" to anyone who crosses paths with him.
Now the focus of the question concerns that weird outgrowth on Melalo's back, which in the official legend is his second head. In real life, however, that "second head" would instead be some kind of casque, like the one you find in hornbills or cassowaries. But bird casques are usually placed on the head, which doesn't affect the hornbill's overall ability to fly.
I have found nothing mentioning that Melalo could fly, but the point of having a casque at the BACK rather than the head still takes precedence. Why would Melalo and his species--or genus--have such a thing on his back?