The Cacodemons of Doom 64 are ressurrected carcasses of those from Doom 1, resurrected by the Mother of All Demons. They are made from systematically altered dead carnage remade back into corrupted living tissue. The mutations were devastating. The Demons have returned stronger and more vicious than before.
They float in the air, belch ball=lightning, and have one horrendously big mouth. If you get too close to one of these monstrosities, you're toast.
It underwent major mutations, becoming beige brown, with a single yellow-green eye, and gaining two arms with broken chains attached, and a rather terrifying face. It resembles Doom II's original Pain Elemental.
Instead of a screech it lets out a loud, frightening hiss when spotting the player, and the body of the monster has animation frames (mostly in the way it swings its arms when in flight), whereas the original Cacodemon floated in a motionless manner.
Behind the scenes