Astral Mage is a character created for the DC Comics one shot mini-series called Justice League of America: Another Nail. He appeared in volume #1, volume #2. He appears originally as Astralad in The New Adventures of Superboy #4 - Look At Me World--I'm Astralad!
History: Pre-Crisis of Infinite Earths
Joseph Silver works as a scientist in a dream-research facility in Metropolis. Although he has a brilliant career, he is deeply unsatisfied because he is ugly and lacks all social skills. He thinks back to his childhood in Smallville when he was called "Mr. Inferiority Complex". He is deeply jealous of "the other mother's boy" in his class, Clark Kent, who made it to be a popular anchor man on television.
Joe Silver decides to use his years of research to turn his life around and tries out his invention of a machine that allows his astral body to travel back in time and possess his teenage body to give his younger self some badly needed self-confidence.
It soon becomes clear that while the older Silver possesses Joey's body, he is more than a mere human: He easily tosses two bullies halfway through the gym.
During a concert of up and coming beat band The Doodles, Joey makes his first appearance as Astralad, having used his powers to turn himself into a handsome, athletic stud with a manly mane of black hair and black and purple costume.
Superboy recognizes his classmate with x-ray vision and uses his super-breath to suck him away from the crowd. He confronts him with his real name (how would Superboy know a nobody? Giving away your secret ID here Kal, tsk tsk), and Astralad replies that he does not intend to keep his identity a secret. He wants all of Smallville to know that Joe Silver is a super hero now. He easily traps Superboy with energy rays from his fingers and tosses him into orbit.
Later, Astralad approaches Lana Lang and tells her he plans to form a super-team with Superboy. Lana says his voice sounds familiar, and Joe takes off his mask and transforms his face back to his normal features. But the girl cannot recognize him, as Superboy uses his heat vision to make the air flicker between them. He then disperses the sound waves to keep Lana from hearing Joey say his name.
Astralad then stops bank robbers from getting away in a balloon, but Superboy steals his thunder by knocking the wind out of him and taking the robbers to the police himself.
After Superboy stops Joe once more of revealing his other ID, he confronts Astralad and explains to him how dangerous it could be for him and his family to just come out like that. Astralad thinks he is just jealous and flies off.
Astralad breaks through the Kent's roof and kidnaps Clark. He says he wants to use him as a bargain chip in his dispute with Superboy. In a cave outside Smallville, Clark claims to recognize Joe's voice, and Astralad tells him the full story of astral time travel and such.
Clark pretends to lose his temper and knocks Astralad through the cage. Astralad lashes out with energy beams from his eyes, which tear most of Clark's street clothes off and reveal his Superboy costume. He convinces Astralad that his subconsciousness must have influenced his dream powers to turn Clark into Superboy to show him the error of his ways.
Astralad realizes that it's wrong to want to change the past and leaves Joey's body to travel back to modern day Metropolis, where he looks up an old Smallville newspaper in which Superboy speculates that the suddenly-departed Astralad must have been an alien.
He sees a Clark Kent billboard and muses that Clark as a super hero is even more ridiculous than he himself.
History: Justice League of America: Another Nail
As with its predecessor, Another Nail occurs outside of the official DC Universe continuity, belonging to the Elseworlds collection of stories. Many of the plotlines from its predecessor are expanded and important moments from the previous story arc are told from different viewpoints, revealing new information.
In this continuity it is shown that the Martian Manhunter is stationed in the Justice League Satellite floating above the planet Earth. Here we find three new candidates that are vying for permanent membership into the Justice League. Firestorm, Halo, and finally Astral Mage who is this universe's version of Astralad. Astral Mage joins the Martian Manhunter and the other recruits in trying to stop the unraveling of the universe as we know it by an otherworldly organism many times the size of our own solar system called the Limbo Cell.