It could be a young and ambitious devil who has grown tired of the old ways of the underworld. He might see the current power - holders as corrupt and decides to take matters into his own hands by declaring war.
Spawn comics have indeed come to an end. The decision to end it might have been based on various factors such as creative direction, sales figures, or the story reaching a natural conclusion.
Spawn can be a good comic, depending on your preferences. It has a dark and gritty tone, along with complex themes that some people really enjoy. But if you're not into that kind of style, it might not be for you.