Dimir Tempo leans on Thoughtseize and Force of Will/Daze to strip and counter our plan while Wasteland cuts our fixing, so Leyline of Sanctity (free from an opening hand) makes us immune to their targeted discard like Thoughtseize. Into the Flood Maw answers a resolved Murktide Regent or Tamiyo, Inquisitive Student cheaply, buying time to assemble Dread Return or Bridge from Below triggers. Bridge from Below is weaker here since they have little incidental removal to fuel Zombie tokens off our own creatures dying, so we trim some copies for interaction. Unmask comes down slightly since our own hand disruption is less impactful against a deck that plays around it with free counters.