Trinisphere punishes their cantrip-heavy, low-curve plan (Brainstorm, Ponder, Stifle, Daze) by forcing every spell to cost at least three, badly disrupting their tempo game. Containment Priest doesn't stop much reanimation here but is still a solid flash body that dodges sorcery-speed removal and can block Phelia's exile-and-return shenanigans by simply trading in combat. Chalice of the Void at one is excellent, locking out most of their one-mana interaction and cantrips entirely. Cut Chrome Mox, which telegraphs information to a deck full of free countermagic, and Sheltered by Ghosts, which is a clunkier answer against a deck that already has plenty of ways to bounce or remove your threats.