Missing sideboard cards? The full 15-card sideboard runs about $53.13.
Buy sideboard on ManapoolCrimson Acolyte gives protection from red, making it and any creature it targets immune to Lightning Bolt, Fiery Temper, Lava Dart, and Fireblast, which is enormous against a deck with almost no non-red ways to interact. Scattershot Archer doesn't do much here since the opponent has few fliers, but it's a cheap defensive body; the real plan is walling the ground with Overgrown Battlement and Axebane Guardian while Crimson Acolyte shuts off their removal on key blockers. Cut the slower value creatures that don't affect the race, since this matchup is about surviving the clock, not grinding card advantage. Guttersnipe and Kessig Flamebreather punish the opponent's own instant and sorcery spells, not ours, but they're still bodies we need to be able to race or wall efficiently.
Faerie Macabre can exile Gurmag Angler's delve fuel from their graveyard, meaningfully taxing their ability to cheat it into play cheaply, and it can block their Ninja of the Deep Hours on the ground and serve as a flying blocker against Spellstutter Sprite. This matchup is primarily a battle of resolving threats through Counterspell and Spellstutter Sprite, so keep our full ramp suite to play around counterspells by deploying multiple threats per turn. Snuff Out and Cast Down are their removal, so our go-wide walls plan (Axebane Guardian, Overgrown Battlement) is well positioned since they can't kill everything. Trim only the weakest value creatures to bring in graveyard disruption without touching our core engine.
Faerie Macabre can discard itself to exile cards from graveyards, which strips the instants and sorceries that make Tolarian Terror and Cryptic Serpent cheap, and also hits their self-mill fuel from Thought Scour and Mental Note before it piles up. Scattershot Archer kills Delver of Secrets once it transforms (it only has flying on its transformed face, where it has 1 toughness) and can repeatedly snipe it when they rely on it for pressure. Cut our slower value pieces since we need efficient answers to their card-selection-into-big-threat plan rather than more raw card advantage. Keep our core mana creatures in since we still need to out-value them on board once their counterspells are exhausted.