Doomsday wins out of nowhere once it assembles its five-card pile, protected by Force of Will and Daze, so our best plan is maximizing proactive disruption on their hand before they can go off. Bitter Triumph isn't really for killing their creatures (they run almost none) but Thassa's Oracle is their only real target — more importantly, keep Thoughtseize and Unmask at full count since stripping Doomsday itself or a counterspell is the highest-leverage play. Cabal Therapy is clunky here because sacrificing a creature to flashback it slows us down in a race where speed matters, so trimming it for Bitter Triumph's flexibility (can still kill Thassa's Oracle) is a reasonable swap. This matchup is still primarily about disrupting their combo pieces, not combat.