Claim the Firstborn is weak since their creatures are cheap and disposable, not worth stealing for a single attack, and Bloodtithe Harvester's ETB is fine but its removal ability is too slow against their aggressive clock. Firebending Lesson is a cheap instant that deals 2 damage to a creature, enough to answer Monastery Swiftspear, Soul-Scar Mage and Emberheart Challenger. Ruinous Waterbending gives us a sweeper against their low-toughness creatures, though it hits our own small creatures too, so plan around that. The Legend of Roku digs three cards deeper to refill our hand after Reckless Rage or Sunspine Lynx-fueled exchanges, and its transformed side is a legendary creature with Firebending 4 that can eventually make 4/4 Dragon tokens with flying for {8}. Lean hard on Fatal Push, Witch's Oven, and Cauldron Familiar to stabilize the early race against their burn and creature pressure.