The Rock's key blockers, Wall of Roots (0/5) and Wall of Blossoms (0/4), both survive Pyroclasm's 2 damage, and their real threats like Ravenous Baloth (4/4) and Krosan Tusker (6/5) are far outside its range, so Pyroclasm offers little here and stays in the sideboard. Pernicious Deed is their main sweeper and your removal suite (Lightning Bolt, Incinerate, Shock) already answers Nantuko Vigilante and smaller permanents efficiently. No sideboard changes are recommended; lean on your low curve and direct damage to the face to outrace their card-advantage-heavy, slower plan before Pernicious Deed can reset the board.