A downhole system for multistage fracturing a subterranean formation that includes a first cluster of valves arranged on a tubular in an initially closed position. There is a second cluster of valves downhole of the first cluster, which is also arranged on the tubular in a respective initially closed position. The system has a plugging device operably coupled with a workstring, that is moved into the tubular. The plugging device is operable to move from a run-in configuration to a set configuration.