Izzet Delver is a fast clock built around Dragon's Rage Channeler, protected by Force of Will, with Wasteland to strip our mana. Static Prison is our best answer, exiling a delirious Dragon's Rage Channeler for a single mana until it leaves the battlefield, and Swords to Plowshares handles their threats just as cleanly. We shave Karakas, which has no targets here, along with Pithing Needle and a couple of artifact mana rocks (Mox Opal, Manifold Key) since surviving their clock matters more than maximizing our own speed.