This WU deck is loaded with countermagic (Force of Will, Daze, Stifle, Consign to Memory), and Defense Grid makes nearly all of it much more expensive to cast on your turn, giving your Aluren and Show and Tell plans a much safer window to resolve. Veil of Summer's real value is that spells you control can't be countered this turn, so hold it up and cast it in response to a counterspell to push your key spell through. It also draws a card if they have cast a blue or black spell that turn, which this deck will usually have done. Veil does not protect you from Swords to Plowshares, since that spell is white. Omniscience is too slow against a deck full of efficient interaction and Tamiyo-fueled card advantage, so it's cut along with the Boseiju, whose channel ability has few high-value targets here and gives them a replacement land.