WBR is an aggressive midrange deck with recursive threats like Bloodghast and Carnage, Crimson Chaos, so you want durable blockers and hand disruption to stay ahead of their pressure. Leatherhead, Swamp Stalker blocks and attacks well against their small-to-medium creatures and has hexproof to dodge their removal early. Duress strips a Cool but Rude or Practiced Offense before it lands, denying them tempo. Cut Nowhere to Run, Outrageous Robbery, Sandman, Shifting Scoundrel, and Bedeck/Bedazzle, all of which are too slow or narrow against a deck built to apply constant pressure.