Dimir Tempo leans on Force of Will and Daze to protect Murktide Regent or a flipped Tamiyo, so Snuff Out gives us a free way (paying 4 life rather than mana) to kill their key nonblack threats without being taxed by their countermagic. Cabal Therapy is weaker here since they often hold up only one or two relevant cards and can rebuild with cantrips, making blind discard less reliable than against combo. Keep Thoughtseize and Unmask at full count to strip their last answer before resolving Griselbrand or Atraxa, and prioritize reanimating threats on turns their mana is tapped out from Wasteland or cantrips.