This is the Domain Zoo mirror, decided largely by efficient interaction and tempo. Obsidian Charmaw destroys a nonbasic land on entry, hurting their fetchland-and-dual manabase and domain count, while also being a flying body their removal suite (Fatal Push, Lightning Bolt) handles less cleanly than our ground creatures. Containment Priest disrupts their Phelia, Exuberant Shepherd blink value and exiles anything that would enter the battlefield without being cast. Stubborn Denial is symmetrical since both decks run it, so trading it for mirror-specific hate is better, and Lightning Bolt is often too small against their Territorial Kavu and Scion of Draco, making both easy cuts.