This Gruul deck relies on Urza's Saga, Eldrazi Temple, and Ugin's Labyrinth for value and ramp, so Meltdown at X=0 or X=1 cleanly answers Urza's Saga's Construct tokens and other cheap artifacts before they take over. Nihil Spellbomb and Surgical Extraction disrupt Malevolent Rumble's graveyard fill and can strip away cards it puts into the graveyard, plus Nihil Spellbomb replaces itself. Lightning Bolt actually kills their small creatures like Basking Broodscale and Glaring Fleshraker just fine, but it's a weak answer to their bigger threats like Emrakul, so trim it for artifact and graveyard hate; Cling to Dust is similarly low-impact against their bigger threats.