He wears a black cloak and an "utility vest" that seems to carry more items than Batman's utility belt ever did.
He may be a member of the Brooklyn Sentinels. He appears with Bliss and an unnamed heroine (possibly Pixie) during a fight between She-Beast, Superchick, Nacht, Gloriana, Belphoebe, Hazard, Sizzle and the Brooklyn Sentinels versus Anti-Champion, an unknown supervillainess dubbed "Lady Anti-Champion," and their minions.
Shadowmage got his start when a vampire named Lepra Netrebnic targeted his mother because she had some piece of cursed jewelry. Shadowmage discovered the bank where Netrebnic hid his considerable funds and moved all the money into another account, reducing the vampire's options. After he staked Netrebnic, the money had no owner, and he kept it to financially seed his career.
Sometime around 2001, the supervillainess Witch Queen became pregnant by him under unrevealed circumstances. When he discovered the existence of a son, the custody battle was ferocious—one of the lawyers retired to a monastery afterwards. Since then, they have a sort of a truce, in which the boy lives with his father and spends vacations with his mother, and refrains from passing information either way.
The cost of sending their son to Whateley forced him and the Witch Queen into a closer collaboration.