Izzet Delver pressures with Dragon's Rage Channeler and Murktide Regent behind Force of Will and Daze, so Snuff Out lets us remove either threat for free (paying 4 life) even when they're holding up countermagic, which our mana-intensive spells can't always play around. Cabal Therapy is less reliable here since their threats resolve early and their hand empties fast into cantrips, so discard loses value compared to removal that answers a stuck threat. Keep Thoughtseize and Unmask at full count to clear a path for Griselbrand or Atraxa before they can Force of Will it, and be mindful of Wasteland limiting our access to Dark Ritual-fueled turns.