Mono Black Aggro has almost no noncreature spells worth countering after Thoughtseize, so Spell Pierce is dead weight and comes out. Soul-Guide Lantern exiles a graveyard card on entry, disrupting their Stitcher's Supplier mill and recursive Bloodghast plan, and Scorching Shot's 5 damage is big enough to cleanly kill Gray Merchant of Asphodel or Baron Helmut Zemo before they generate value. Monstrous Rage is too fragile against their efficient removal suite of Fatal Push and Bitter Triumph, so it comes out as well. Race them early since this matchup comes down to who establishes pressure first, and use your removal on their devotion payoffs rather than small creatures.