Mystic Forge Combo relies heavily on artifact mana rocks and engines like Grim Monolith, Mox Opal, The One Ring, and Mystic Forge itself, so Null Rod is a powerful answer that shuts off most of their key activated abilities. Barrowgoyf provides a resilient clock that pressures them while they try to assemble their slow artifact engine across multiple turns. Snuff Out is weak since their creatures are mostly colorless artifact creatures that come down late, and Bilbo does nothing proactive against a combo deck, so trim both for more impactful disruption. Keep Wasteland and Thoughtseize in as key tools to deny their Urza lands and strip their combo pieces before they can go off.