Izzet Spellementals grows Hearth Elemental and Eddymurk Crab as it chains cantrips together, so removal that answers a specific evasive or growing threat is much better than our slower mana sinks. Erode and Sheltered by Ghosts each remove their best threat regardless of size, while Soul-Guide Lantern can strip a card from their graveyard to slow Eddymurk Crab's cost reduction from instants and sorceries piling up. We already have plenty of exile-based removal in Seam Rip for cheap permanents, so trimming a couple copies for more universal answers to their bigger threats is worth it since Seam Rip whiffs on their 5/5s.

Mono Green Landfall wants to chain fetch-lands into Earthbender Ascension and Mightform Harmonizer triggers, snowballing power quickly, so removal that answers their best threat is key. Erode and Sheltered by Ghosts let us proactively remove Mightform Harmonizer, while Erode can also target an earthbent land creature before it doubles in power off landfall, keeping their board from running away from us. We trim our own slower cards (Ouroboroid, Multiversal Passage) since this race is won by disrupting their engine pieces rather than out-grinding them.

Jeskai Control wants to trade one-for-one with removal like Firebending Lesson, Combustion Technique, and Iroh's Demonstration while Jeskai Revelation and Great Hall of the Biblioplex grind out the long game, so cheap mana dorks that die to their sweepers (like Iroh's Demonstration or Day of Judgment) are lower value here. Balustrade Wurm is uncounterable and a 5/5 trampler that survives their damage-based removal and forces them into a real removal spell, while Erode gives you a way to answer Thor, God of Thunder or a resolved Ral, Crackling Wit. Soul-Guide Lantern strips their Lesson-fueled graveyard value and cracks for a card later. Keep your curve lean and play around Day of Judgment by not overextending into their sweepers.