Annul can counter Phyrexian Dreadnought as an artifact creature spell, and it also hits Lotus Petal and Dragon Breath, so it has real targets in this matchup. It cannot counter Sutured Ghoul, which is not an artifact or enchantment. Prohibit is actually well placed here, since Lotus Petal, Reanimate, Hermit Druid and Phyrexian Dreadnought are all within its mana value range, so we keep it and trim an expensive Decree of Justice instead. This is a small, surgical swap because our mainboard Swords to Plowshares already answers a resolved Dreadnought or Sutured Ghoul, and Powder Keg can handle Dreadnought. Our counterspell suite (Counterspell, Mana Leak, Prohibit) is already well-positioned to fight their combo pieces like Reanimate and Shallow Grave.