According to notes (k-z), he is one of the more powerful Mahjarrat.
During the The World Wakes quest he will show you that since you have open the resting chamber of Guthix others have noticed this and will come as well.
During the Fate of the Gods quest he will bring the World gate from the Shadow Realm into the material ealm.
During the 2016 Easter Event you will help the Easter Bunny stop Sliske building his own chocolate factory.