Boros Aggro races with Dragons like Nova Hellkite and Magmatic Hellkite backed by burn like Burst Lightning, so this is a mirror-race where Duress strips their removal or a key noncreature threat before it can be used against our board, and a second Mai, Scornful Striker punishes any noncreature spell they cast for 2 life each, adding up against their aggressive clock. Timeline Culler's small body trades poorly against their 4/5 Dragons, and Lich's Relic's slow equip speed is too clunky in a fast race. Prioritize removal on their Dragons and keep pressure high since this matchup comes down to who runs out of resources first.