Izzet Affinity runs a large pile of cheap colorless artifacts (Mox Opal, Chrome Mox, Lotus Petal, the Baubles, Chalice of the Void, Pithing Needle, Tormod's Crypt, Skateboard) alongside Seat of the Synod and Urza's Saga Construct tokens, which makes Meltdown a strong sweeper. At X=0 or X=1 it wipes their mana rocks, Seat of the Synod, Drone and Construct tokens, and (at X=1) Skateboard and Pithing Needle. Ratchet Bomb does a similar job from the other side: sacrificed early it clears zero-cost nonland permanents and tokens, and with a few counters it can hit their three-mana creatures like Emry, Council of Reeds and Pinnacle Emissary. Don't count on it for Kappa Cannoneer, which would need six counters. Consign to Memory is narrower than a blanket answer to their spells: its spell mode only counters colorless spells, so it hits the Moxen, Petal, Baubles, Chalice, Needle, Crypt and Skateboard but not the blue or blue-red cards like Thoughtcast, Emry, Council of Reeds, Pinnacle Emissary or Kappa Cannoneer. Its other mode counters triggered abilities, which lets it stop Pinnacle Emissary's Drone trigger, Kappa Cannoneer's counter-and-unblockable trigger, or Council of Reeds' copy trigger. Replicate can add extra copies to cover several colorless spells or triggers in one turn. Into the Flood Maw and Spell Pierce are trimmed because their cheap artifacts and tokens make one-for-one tempo plays low impact here, and the extra Preordain and Flow State are cut for interaction density since this matchup is about disrupting their engine, not digging.