Abstract: Reaction vessels, cartridges, devices and methods for facilitating high-level multiplexing are described herein. Such reaction vessels can include a planar frame defining a fluidic path between a first planar substrate and a second planar substrate, a fluidic interface is located at one end of the planar frame with a pair of fluidic ports, a well chamber and a pre-amplification chamber. Devices for spotting reagents in wells of high-level multiplexing reaction vessels and improved reagent solutions are also described herein.