Belcher is a blue-heavy combo deck full of countermagic (Counterspell, Force of Negation, Spell Snare) and card selection to protect and assemble Goblin Charbelcher kills, making Mystical Dispute a cheap, efficient answer to nearly their entire deck's blue spells. Street Wraith does nothing to interact with their combo and is the easiest cut since we need maximum disruption density to stop them from resolving a lethal Goblin Charbelcher or protecting it with countermagic. Force of Negation and Subtlety are premium here to strip their protection spells before they can combo off. This matchup is a race to disrupt first, so mulligan aggressively for interaction and be ready to fire off Living End the moment you have a critical mass of suspended threats.