Domain Zoo is an aggressive deck built around Ragavan, Territorial Kavu, and Scion of Draco backed by Stubborn Denial and Spell Snare protection, so Veil of Summer protects your discard spells from their countermagic while granting hexproof from their Fatal Push. March of Wretched Sorrow and Professor Dellian Fel provide removal for their threats while gaining life to keep you alive against their aggressive pressure. Requiting Hex only hits mana value 2 or less which is narrow against their curve topping out with Scion of Draco, and Plunge into Darkness is too slow against a deck actively racing you, so trim both for the more impactful removal and protection.