Ominous Nebula is a technique of extreme concentration where Zeldris revolves his dark energy around him at immense speeds to the point of seeming invisible, creating a vortex that surrounds and attracts all living beings around him. This power makes the air flow and creates a vacuum and everything that comes in contact with it is sliced by Zeldris at a god-like speed by pure reflexes, making this technique a Full React「
Ludociel, leader of the Four Archangels, states that the speed of this technique surpasses even his Grace, Flash. By enlarging the demon mark on his forehead, Zeldris can ensure that Ominous Nebula's overall power skyrockets, magnifying the power greatly, and increasing the damage dealt as well as the speed and power of the vacuum created. Whereas Ludociel, Merlin and Escanor could just about resist its original power (albeit with great difficulty), they were left helpless infront of its increased power. Even powerful demons such as Chandler and Cusack were forced to immobilize themselves to protect themselves from being drawn in by the all-encompassing vacuum of Ominous Nebula.