BRG is a grindy sacrifice/value deck full of small creatures (Callous Inspector, Gene Pollinator, Greedy Freebooter) that Doc Ock's Tentacles and Basilisk Collar don't close out fast enough against, since the opponent has plenty of removal like Deadly Precision and Requiting Hex waiting to two-for-one you. Erode is clean, efficient removal for their early threats and bigger bodies like Mutagen Man. Shattered Acolyte adds a cheap lifelink body and insurance against The Ooze or any artifact/enchantment threats they bring in game 2. Keep the aggressive equipment plan with Leyline Axe and Thorin intact since you want to race before their grindy card advantage takes over.

Izzet Spellementals relies on casting a critical mass of cheap instants and sorceries to grow Hearth Elemental and enable Eddymurk Crab's cost reduction, so Rest in Peace is devastating, exiling their graveyard and shutting off any delve-style discounts while also denying Traumatic Critique and Prismari Charm any recursive value. Voice of Victory is excellent here too, since it stops them from responding with Opt, Sleight of Hand, or removal during your turn, protecting your attackers. Doc Ock's Tentacles and Basilisk Collar are cut because this matchup is about denying their engine and racing, not grinding incremental value. Raubahn comes out since his ward tax doesn't matter against a deck with little hard removal, and the slot is better used proactively.

This is a mirror-ish aggro race against big flying Dragons like Nova Hellkite and Magmatic Hellkite, so Erode gives you clean, instant-speed removal for their top-end threats before they can swing. The Queen of Dale punishes their noncreature spells like Burst Lightning and Erode by forcing a recruit trigger that nets you cards and bodies. Doc Ock's Tentacles and Basilisk Collar are too slow in a race this fast, and Raubahn's ward tax isn't very relevant against a deck without much targeted removal. Keep your low curve and equipment synergies intact to out-tempo them.