Ghostwalker was the best mage among GD's in the Fourth World, and the best summoner. I don't think that changed, as Vasdenjas is dead (Dunkelzahn inherited his title of Loremaster), and Dunkelzahn also - those were the only two that could possibly be any competition in that matter.
He usually made the front entrance approach - like in ED with the whole war vs. dragons that Thera brewed after finding out that dragons also know the protections from the Scourge. They began targeting dragons, but lost their Behemoth (a huge flying castle-airship) in the process, and when they reached GW's lair, it was empty. Soon after, major players on Thera who were involved or profited from the dragon hunt started dying, and a dragon looking just like GW was seen sitting on the Sphinks, in the middle of the imperial city of Thera, just by the governor's palace every time someone 'mysteriously' died...
In short: he went to the enemy's capital and took revenge on his own. And soon after therans announced they will leave dragons alone if they don't spread information on the protection rituals - which they weren't really, at least not for free.
And who was the major power and political player in Earthdawn? Icewing/Ghostwalker. He even had his pet dwarven kingdom of Throal that was trying to unite all of the province against the therans...
Oh, and like Dunkelzahn, he really doesn't like blood magic, and such. It was the theran specialty - like their ships were fueled by draining lives of slaves, and such...