Izzet Delver's clock comes from Dragon's Rage Channeler and Murktide Regent, both of which die cleanly to Static Prison or Portable Hole before they get big. Warping Wail is flexible here — kill an early Delver of Secrets or Channeler with its removal mode, or counter a cheap Lightning Bolt/Daze when they're light on mana. Since this matchup is a race decided by who lands relevant plays first, trim the top-heavy Tezzeret and situational Fleshraker copies for efficient answers. Keep Chalice of the Void in, as setting it to X=1 can strand a huge portion of their Bolt/Brainstorm/Ponder/Daze suite.