"Adam" was the first humanoid being created by Ex Nihilo in his effort to create life anew on Earth. But as soon as he emerged from his cocoon, his ability to speak in Builder Machine Code made Nihilo and his sister Abyss think something was wrong. He was later taken into custody of the Avengers in order to study him and try to decode his language. Tony Stark managed to decode his name into "Blackveil."
After a therapy session with the new Captain Universe, Shang-Chi was told the presence of it was because the universe was dying. Both Captain Universe and "Blackveil" met, and as she managed to translate correctly his language, she discovered his name was Nightmask and he was announcing that the White Event was coming to Earth. In that moment, a blaze of lightning from outer space hit the Earth.
Nightmask led the Avengers in finding the Star Brand host, Kevin Connor, who was located at the ruins of a college, destroyed his empowerment.
After a brief battle with the Avengers, Kevin Connor was taken by Nightmask to Mars, in order to seek help from Ex Nihilo. In the meantime, he explained to Starbrand what caused his powers and what his purpose was. On Mars, Ex Nihilo revealed that the White Event was caused by his attempts to make Earth sentient.
Nightmask teleported Connor and himself to Croatia, one of the places modified by Ex Nihilo, where strange creatures started forming a brain-like structure. The "brain" tried to absorb Nightmask, but he was rescued by Starbrand, who accidentally killed the organism in the process, "killing" the Earth's potential consciousness. The Avengers arrived on the scene and attempted to stop them. They fought back until Starbrand surrendered. As they were out of options, the heroes decided it would be better for Starbrand to be off the Earth and placed him in Tony Stark's Dyson Sphere which was under construction around the Sun, in the company of Nightmask.
When Captain Universe sensed a new threat coming to Earth, she advised the Avengers to recruit Nightmask and Star Brand into the team, which they did.
Time Runs Out
After the Avengers fell into S.H.I.E.L.D. authority, Star Brand and Nightmask left the team to investigate the decay of the universe. For some reason, Nightmask began to rejuvenate. They returned to Earth when they received a message from Sunspot, inviting them to join his own Avengers team as there had been new progress on the research related to Incursions.
Using A.I.M.'s resources, Sunspot managed to put into operation a machine capable of transporting individuals across the Multiverse, in hopes of finding the source of the decay of the Multiverse, and a group of them, the "Multiversal Avengers," embarked in said mission. Star Brand was among this heroes.
In their journey, the Multiversal Avengers arrived to the base of the Black Priests, whom they believed to be enemies, as they would destroy alternate Earths. After discovering their true motivation, that of saving the Multiverse, the Multiversal Avengers allied with the Black Priests, and were informed of the true enemies they had to face, the Ivory Kings and Rabum Alal. While the Black Priests tried to find Rabum Alal, the Multiversal Avengers would set out to find the Ivory Kings (also known as the Beyonders).
The Avengers traveled across numerous universes, navigating the map left by the Mapmakers. The use of his powers caused Nightmask to rejuvenate, and the final jump across universes caused him to revert into inexistence.
Nightmask is an artificial being created from Ex Nihilo's machine's to be the first of a new race humans. Yet somehow, he was altered with aspects not programmed into his genetic code. This change may somehow be related to the universal transcendent advent called the White Event, bestowing him strange new powers.
Techno-Communication: Nightmask has the ability to control and radically alter machines. Moreover, he can not only manipulate technology, repurposing it to his will, but can somehow communicate with it as though it were sentient. Currently it is unknown how he does so, whether it be psionic, physical, cosmic or some other outer source that enables its use, but it's believed to be related to the Builders.
Energy Halos: Nightmask's powers often manifest themselves as light-blue energised patterns in the form of energy discharges, often accompanied by strange symbols gravitating around and off of his skin and clothing. It is assumed that these symbols give him other abilities, such as:
Portals: Possesses vast matter/energy transportation ability enabling instantaneous travel to any point Nightmask can think of. The range so far can currently stem to different points in the multiverse and just as easily travel from Earth to Mars. it would seem like previous incarnations the nightmask ports through the Superflow system to dip in and out of points in time-space.
Energy Blast: Through his halos Nightmask can disperse and direct concussive force blasts from his person.