Abyss, known as the Armor of Erosion, is the antagonist in Marvel vs. Capcom 2: New Age of Heroes. He was responsible for a mysterious wind that spread across the world, killing plantlife in its wake. This phenomenon prompted numerous heroes and villains to band together and investigate. He's something akin to entropy incarnate, a fabled monstrosity that would bring the world back to primordial times, killing all life in the process.
Abyss's true form is apparently that of a large glowing sphere that hovers around in the background. Abyss changes into three different forms when fighting.
This is the 2nd form of transformation, After the 1st form is defeated, the armor melts into the floor and the temple crumbles, leaving the fighters standing in a green pool of slime. The abyss sphere floats in the background as the second form reveals itself; a small green humanoid capable of creating paralyzing bubbles, shooting fire and energy beams, and sinking into the floor to avoid attacks. After the 2nd form is defeated, the green slime turns red and a large demonic beast forms around the Abyss sphere. This third form attacks with powerful energy attacks and sheer brute strength. If this form is defeated the sphere apparently loses its power and the cave and island the monster inhabits begins to sink.