Eldrazi Tron runs on artifacts like Mind Stone, Expedition Map, and especially Chalice of the Void, so Meltdown at X=0 or X=1 can blow up Chalice or Map before it locks you out. Damping Sphere is excellent against their Urza's Tron lands and Eldrazi Temple, which normally produce 2-3 colorless mana each. Cut Burning Inquiry and Practiced Offense since neither helps you fight through Chalice of the Void or a resolved Karn, the Great Creator, and you need every card to be live disruption.