Mono Red Rally floods the board with small creatures like Burning-Tree Emissary, Clockwork Percussionist, and Rally at the Hornburg tokens before alpha-striking, so End the Festivities is excellent, dealing 1 damage to the opponent and wiping their 1-toughness swarm (Clockwork Percussionist, Goblin Bushwhacker, Voldaren Epicure, Rally tokens) in one shot. Note that Burning-Tree Emissary is a 2/2 and survives it, so you'll need another answer for those. Searing Blaze is also strong since most of their creatures have 1-2 toughness, letting it double as removal and reach, and with landfall it deals enough damage to kill the 2-toughness creatures too. This is a race where both decks want to go under each other, so cut the slowest card-advantage spells (Sazacap's Brew, Highway Robbery) to keep the curve low and prioritize interaction that also hits face. Keep the full core engine intact since we're both aggro decks and need maximum speed and damage output.