Affinity is an artifact-heavy deck full of nonbasic artifact lands (Ancient Den, Seat of the Synod, Vault of Whispers, plus the Bridges), artifact creatures (Refurbished Familiar, Utrom Monitor, Baleful Strix) and artifacts like Cryogen Relic. Vandalblast overloaded for {4}{R} is a one-sided mass destruction effect that can wipe out their artifacts, artifact creatures and much of their manabase at once. Their white creatures, Kor Skyfisher and Glint Hawk, are not artifacts and will survive it. Relic of Progenitus can exile their graveyard to blank Blood Fountain's creature recursion, though its main role here is incidental. Crop Rotation and Bonder's Ornament are easy cuts since this matchup rewards proactive disruption and big bodies over mana smoothing against a deck that floods the board quickly with small threats. Prioritize casting Vandalblast once they've committed several artifacts to the board to maximize the blowout.