Discard has limited value since the deck is nearly all counterspells and cantrips, not creatures, so Ravenous Rats and the slow Graveborn Muse come out. Engineered Plague naming Phyrexian Dreadnought shrinks it to an 11/11 and, combined with sacrificing creatures for the trigger, can make the sacrifice math fail outright. Keep leaning on Duress and Cabal Therapy to strip Stifle/Vision Charm before they commit to the Dreadnought play, and use Mishra's Factory to pressure them while they're tapped out protecting the combo.