WUBG plays Oath of Druids to cheat Terravore into play using creatures revealed off the top of their library, and Terravore's size scales with lands in all graveyards including yours. The extra Tormod's Crypt lets you proactively exile your own or their graveyard to keep Terravore small and can disrupt any accidental synergies, all for zero mana investment. Arcane Denial is a weak swap since this deck is already grindy and card-advantage-oriented with Sylvan Library, so giving them another card is not worth countering a single spell. Race them with your combo before Sphere of Resistance and repeated Wasteland/Rishadan Port activations grind you out.