4c HollowOne wants to dump its hand via Burning Inquiry and Faithless Looting to cheat out Hollow One, Vengevine, and Detective's Phoenix for very little mana, so Trinisphere is excellent, taxing their one-mana enablers (Faithless Looting, Burning Inquiry) up to three mana and badly disrupting their fast starts. Aside from Abstergo Entertainment, the rest of your sideboard does not interact with their graveyard directly. Cut Summoner's Pact since its deferred payment is dangerous against a deck this explosive, and trim one Malevolent Rumble to fit Trinisphere while keeping your ramp plan intact to race them to Scapeshift or Primeval Titan.