Gruul Delirium plays a creature-midrange game with cheap threats like Patchwork Beastie and Wildfire Wickerfolk, protected by Blossoming Defense and Rapid Rescue, and their sideboard brings in Pyroclasm against small creature decks. Bring in all three Sear for clean removal that dodges their protection tricks at instant speed, and add the fourth Nova Hellkite as a bigger, more resilient threat that survives a Pyroclasm and closes the game quickly. Cut a couple of Shock, which their Blossoming Defense can blank, and trim Magebane Lizard since its toughness makes it a prime Pyroclasm target alongside the rest of your small creatures. Be mindful of overcommitting into a potential Pyroclasm after they sideboard, and look to play around it once the first one resolves.