Mystic Forge Combo leans on artifact mana rocks like Grim Monolith, Voltaic Key, Manifold Key, and Mystic Forge itself to chain into The One Ring and big planeswalkers, so Null Rod is powerful, turning off Grim Monolith, Voltaic Key, and Manifold Key's untap abilities. Consign to Memory counters their colorless spells, hitting Kozilek's Command, Eldrazi Confluence, and Karn, the Great Creator's static ability doesn't stop this since it's a spell not an activated ability on our side. Mockingbird has few good copy targets against their mostly noncreature artifact shell, and Wail of the Forgotten is too slow against their mana-efficient combo turns, so both are trimmed.