Neighboring fused heptamers can support magnetic plasmons due to the generation of antiphase ring currents in the metallic nanoclusters. In this paper, we use such artificial plasmonic molecules as basic elements to construct low-loss plasmonic waveguides and devices. These magnetic plasmon-based complexes exhibit waveguiding functionalities including plasmon steering over large-angle bends, splitting at intersections, and Mach-Zehnder interference between consecutive Y-splitters. Our findings provide a strategy for circumventing significant challenges in the miniaturization and high-density integration of optical circuits in integrated optics, allowing for the development of ultracompact plasmonic networks for practical applications.