This matchup is a fast race, so Red Elemental Blast has no legal targets here: the opponent's deck is entirely red or colorless, with no blue spells or permanents, so it stays in the sideboard. Instead bring in both Go for the Throat to answer Burning-Tree Emissary, Goblin Bushwhacker, Goblin Tomb Raider, Voldaren Epicure, or the Human Soldier tokens from Rally at the Hornburg before the alpha strike connects. Go for the Throat can't target artifact creatures, so Clockwork Percussionist and Gingerbrute are left for Cast Down. Cut the slower value pieces, one Eviscerator's Insight and the Toxin Analysis, which cost you tempo you don't have against a turn-three kill. Keep Cast Down as your primary interaction and prioritize racing/blocking with Writhing Chrysalis's Eldrazi Spawn tokens.