Sylvan Safekeeper protects your key creatures from the targeted removal in this deck, Smother and Snuff Out, by sacrificing a land to give them shroud in response. It does not stop Diabolic Edict or Chainer's Edict, which target you rather than a creature and let you choose what to sacrifice, so Safekeeper can only help there as a cheap body to sacrifice. The extra Cabal Therapy copies (on top of your maindeck one) let you strip their own Duress, Cabal Therapy, or a key threat like Hypnotic Specter before it can disrupt or race you, turning the discard war in your favor. Base Duress is redundant against a deck that already plays symmetrical discard and removal-heavy answers rather than combo pieces worth Duressing preemptively, so trimming it for more proactive Cabal Therapy is better. Krosan Reclamation is a minor cut since this matchup is more about protecting threats and disrupting removal than recurring resources.