Blood Moon turns off their entire Urza's Mine/Power Plant/Tower and Eldrazi Temple/Ugin's Labyrinth manabase, crippling their ability to cast Ugin or Karn, the Great Creator. Hurkyl's Recall bounces their Talisman of Resilience, Expedition Map, and other artifacts, setting them back a full turn of mana development. Vexing Bauble helps tax free spells and gives late-game card advantage. Claws of Gix and one Welding Jar come out since they're too passive against a slower ramp deck we want to race or lock out of mana.