Izzet Phoenix's whole plan revolves around Arclight Phoenix returning from the graveyard after casting three instants/sorceries in a turn, making graveyard exile devastating. Unlicensed Hearse exiles up to two cards from their graveyard at a time, including Arclight Phoenix copies, before they can trigger the return-from-graveyard ability, effectively turning off their best threat. Go Blank adds to this plan by making them discard two cards and then exiling their whole graveyard, which strips Phoenix copies and Treasure Cruise fuel in one shot. Ray of Enfeeblement stays out: at -4/-1 it can't kill Picklock Prankster (1/3) or Arclight Phoenix (3/2), and neither is white. Graveyard Trespasser's graveyard-exile trigger is redundant with Hearse and Go Blank, and its body can be burned out by Fiery Impulse once spell mastery is on or by Lightning Axe, while Sentinel of the Nameless City is too slow against their low curve, so both trim down for faster, more targeted answers.