Izzet Prowess is a fast, low-curve aggro-tempo deck relying on cheap burn and evasive prowess threats, so we need early interaction more than raw size. The second Dismember set gives us cheap, instant-speed removal to answer Dragon's Rage Channeler or Monastery Swiftspear before they get out of hand. Thought-Knot Seer trades well in combat against their small creatures and can strip a key burn spell or Cori-Steel Cutter before it matters. We cut the slowest top-end (Emrakul, Sire of Seven Deaths) since this is a race we can't afford to play passively, and trim Sowing Mycospawn since ramping toward big spells is less relevant when we need to stabilize the board quickly.