Chalice of the Void set to zero counters zero-mana spells like Summoner's Pact and Pact of Negation, shutting down their key tutors and protection. Endurance is the key card here: evoked by exiling a green card, it strips their graveyard, which is critical against Hooting Mandrills delve and any reanimation-adjacent lines, and when hardcast, its body blocks well. Big top-end like Ulamog and Ugin is too slow and clunky against a combo deck that can kill from nowhere with Allosaurus Rider into Neoform or Eldritch Evolution chains, so those get trimmed for cheaper interaction.