This is a cascade mirror where both players race to resolve their namesake spell while disrupting the opponent's cascade trigger. Endurance is your most powerful sideboard tool — flash it in response to their Violent Outburst or Shardless Agent cascade trigger to exile their graveyard before Living End can resolve, leaving them with an empty board. Mystical Dispute upgrades your counter package for the blue-heavy Force of Negation battles that define post-board games, where the blue-on-blue discount makes it far more efficient than generic interaction. Inevitable Betrayal can steal one of their large cycling threats (Generous Ent, Curator of Mysteries, Striped Riverwinder) after they resolve a Living End you couldn't stop. Dead // Gone and Dismember come out because their threats are all too large for 'Dead' to answer, and the tempo from 'Gone' or Dismember is too marginal when the real axis of the matchup is protecting and landing cascade spells.