Gruul Goblins runs red spells and permanents, making Hydroblast an excellent inclusion to counter their spells or destroy their threats, while Compost stays in the board since they run no black cards. Naturalize also stays in the sideboard because they have no artifact or enchantment permanents in their mainboard. Cut Bone Shredder and Mesmeric Fiend, which trade down against their wide token-based aggression.