Amulet Titan relies on Urza's Saga to assemble its artifact toolbox and on bounce lands plus Amulet of Vigor to generate bursts of mana, so Meltdown for X=0 can catch a freshly made Construct token, while X=1 hits an Amulet of Vigor or whatever cheap artifact Urza's Saga's chapter III tutors up. Damping Sphere further slows their bounce-land and Amulet of Vigor mana engine by capping any land tapped for multiple mana. Cut Burning Inquiry and Practiced Offense since neither interacts with their ramp or land-based value engine.