Belcher is a pure combo deck aiming to assemble Goblin Charbelcher or Tameshi, Reality Architect plus artifact recursion for a fast kill, so Damping Sphere increases the cost of consecutive spells cast in a turn, slowing down their multi-spell combo turns. Abrupt Decay can destroy Lotus Bloom or Tameshi, Reality Architect as a nonland permanent with mana value 3 or less and can't be countered by their Counterspell or Force of Negation. Fatal Push and Walking Ballista do essentially nothing against a deck with almost no relevant creatures to kill, so they're cut for proactive artifact disruption; otherwise, race them as fast as possible since our removal package is a supplement, not the primary plan.