Nue

The Nue is a strange amalgamate that was never was supposed to see sunlight. It has a large, fat body, with a thick snake-like tail. It consists of a massive stomach with a incredibly wide mouth similar to a shark's, but with only 2 rows of needle-like teeth, a lump of flesh and eyes where the neck should be, 4  long, thick arms ending in what appear to be hands tipped with sharp, curved claws. It seems to have one consience dictating its body, possibly meaning it is at internal peace. It speaks fluently, and is enraged if any human "attacks" it. It has no family, as its family has forgotten it, since it was kept in the True Lab for so long, and is extremely lonely.

It's made of many monsters, and it's indiscernable how many monsters it is made of, or what types of monsters make it up, besides the teeth. it uses its arms to move and eat.

Humans call it an abombination, freakshow, and overall, ugly, misshapen and awkward. He was discovered on the surface, after devouring several corpses from the nearby cemetary, as well as lost people that attacked it, whose souls he absorbed, gaining extreme power and reach. He was called "the slithering ghoul." It is said that Alphys was going to turn herself into an amalgamate, using the determination extractor set in reverse, because of her guilt, but it pushed her out of the way, and became even more unstable, and devoured a large amount of matter, or rocks, walls,  along with a few monsters, as well as anything in its path to gain the necessary physical matter, and it became as big as Greater Dog when it was done with its feast. It then tried to remove her guilt, but this gave it the aspect of her guilt. It then decided to break the Determination Extractor, so she wouldn't try to destroy herself with determination.

Magic
Main attack: the walls become covered in teeth, and wind blows from the center, trying to force the soul into the fangs.

2nd attack: Releases melted orbs that sometimes appear to have glasses and a crest, similar to Alphys'.