Belcher is a dedicated combo deck aiming to assemble Goblin Charbelcher with an empty or near-empty library via Lotus Bloom and Sea Gate Restoration, so Thoughtseize is premium, stripping their Goblin Charbelcher, Whir of Invention, or key counterspell like Force of Negation before they can combo off. Vexing Bauble is excellent here since it counters any spell cast for free, hitting their Disrupting Shoal specifically since it's cast without paying its mana cost, while also giving you a cheap artifact body and later card draw. The extra Fatal Push is marginal since they run few creatures, but it's still efficient early interaction if they play Hydroelectric Specimen. Abhorrent Oculus, Dewdrop Cure, and Voice of Victory are too slow against a combo deck that can kill from nowhere, and Sylvan Safekeeper doesn't matter since they have no targeted removal for your creatures, so these are the cuts.