Izzet Delver wants to chain cheap cantrips and burn; Damping Sphere taxes each additional spell cast in a turn, slowing down their cantrip-into-threat turns. Dismember cleanly answers Dragon's Rage Channeler and Murktide Regent, both of which otherwise race us down quickly. Grafdigger's Cage is irrelevant since the opponent has no reanimation or graveyard-cast creatures, so it's cut. Keep Wasteland in to contest their Volcanic Island-based mana and slow Cori-Steel Cutter's clock.