This matchup is a durdly ramp-value deck with lots of small colorless creatures (Eldrazi Spawn tokens, Basking Broodscale) and Urza's Saga Constructs, backed by big threats like the 6/6 Devourer of Destiny that Fire Magic can't sweep. Fire Magic at the Fira/Firaga tier clears their small tokens and early creatures. Faerie Macabre can exile cards from their graveyard, such as Malevolent Rumble's milled cards that shrink Emrakul's cost, or strip a key graveyard piece, and it gives us a flexible discard outlet. Meltdown cleanly answers Urza's Saga Constructs, Vexing Bauble, Soul-Guide Lantern, and other cheap artifacts they rely on. We trim some of the worse discard-at-random/cycling pieces that whiff when we don't need the graveyard filled as urgently against their grindy deck.

Izzet Prowess is full of 1-2 toughness creatures (Monastery Swiftspear, Dragon's Rage Channeler, Slickshot Show-Off), so Fire Magic at the Fira tier for 2 generic mana kills most of their early threats in one sweep. We keep our proactive plan almost entirely intact since this is a race and our clock is faster than theirs if we don't get bogged down; Street Wraith is the easiest cut since its evasion matters less than having a cheap sweeper against their swarm of small bodies. Everything else in our sideboard is either dead (Blood Moon doesn't hurt their mostly-basic-adjacent manabase meaningfully since they run plenty of basics, Deafening Silence slows us down too) or not worth the slot in a race we're favored in.

The combo hinges on Blade of the Bloodchief (a 1-mana Equipment) turning Basking Broodscale sacrifices into an infinite loop; Meltdown at X=1 or X=2 blows up Blade (and any Vexing Bauble/Soul-Guide Lantern/Haywire Mite they use as backup pieces) before the loop starts. Wear // Tear gives us an instant-speed way to destroy Blade, and the Tear half can also hit Urza's Saga since it is an enchantment. Faerie Macabre can exile cards from their graveyard, disrupting the piles Malevolent Rumble puts there that feed Shifting Woodland, while also serving as a free discard outlet for us. We cut our weaker discard-matters filler since this matchup is about proactively removing their key artifact rather than racing with our own graveyard plan.