In 1998, the Evil Sorceror worked for a supervillain named Silverclaw (who happened to be an anthropomorphic cartoon cat). Long after Silverclaw's bad guy empire went under, the Evil Sorceror started working for the Guild instead.
The Evil Sorceror main power is magic. As a dark wizard, he is a master of the dark arts. He was also a necromancer as he was responsible for the ressurections on many deceased bad guys that were recruited onto the Guild.