Kasslak is a member of the Daask cell in Sharn and the de-facto authority figure in the Lower Dura district of Malleon's Gate. He prefers to use his power sparingly within the majority goblinoid district, but some statues on the streets are a public display of his power.
Kasslak only uses his power to deal with major disruptions in the district, things that could be considered threats to the community. He won't care if someone is slapping around a couple of bugbears, but if someone were to start killing people or bring the Sharn Watch down into Malleon's Gate, they'd best be prepared to deal with a medusa.