Gruul Broodscale leans on mana-doubling lands like Eldrazi Temple and Ugin's Labyrinth to power out Emrakul and other huge threats, so Damping Sphere caps every land at one mana and slows down their whole plan. Meltdown at X=0 or X=1 can pick off cheap artifacts like Vexing Bauble or Soul-Guide Lantern if they bring them in, though it won't touch their nonartifact lands or creatures. Cut Burning Inquiry since it can hand them extra permanents, and trim Practiced Offense since this matchup is about racing and disruption rather than going wide.