Rotating crossover subassembly

A system for use in completing a wellbore includes a portion of a workstring extending into the wellbore such that a first annulus is created between the workstring and a portion of the wellbore. The portion of the workstring is inserted to a depth corresponding to a base, such as a sump packer that defines a lower boundary of the completion zone. The zone of deployment may be sealed uphole by a second packer included in the workstring. A service tool having an inner sleeve, an outer sleeve, and a rotating mandrel positioned therebetween is provided to deliver fluids and execute completion operations as facilitated by rotation of the mandrel. Rotation of the mandrel allows for control of multiple fluid flow paths, each of which may correspond to a completion process within the zone, without displacement of the service tool in an uphole or downhole direction.