Rakdos Sacrifice fields a swarm of small creatures (Cauldron Familiar, Eyetwitch, the Fable of the Mirror-Breaker token, tokens from Mayhem Devil synergies), so Pyroclasm is excellent, sweeping their 1-toughness Cauldron Familiar and Eyetwitch while also hitting their Bloodtithe Harvester. Redcap Melee cleanly answers Mayhem Devil or Fable of the Mirror-Breaker's token before it flips, both important engine pieces. Monstrous Rage and some copies of Reckless Rage come out since they have Fatal Push and other efficient removal ready to two-for-one the enchanted creature, and Reckless Rage's downside of also damaging your own creature is risky against their small-creature-heavy removal suite. Watch for Bloodtithe Harvester's -X/-X ability threatening your best attacker late game.