Dimir Midrange is loaded with blue spells (Counterspell, Preordain, Subtlety, Psychic Frog) so Mystical Dispute is extremely efficient here, often costing just {U} to stop their Force of Negation or Counterspell protecting their own game plan. Curator of Mysteries is a soft 4/4 flier that dies to Fatal Push or gets outclassed, and Dimir's discard/counter suite makes a slower creature less appealing. This is a grindy matchup where resolving Living End through their countermagic (Counterspell, Spell Snare, Force of Negation) is the primary battle, so keep our own Force of Negation and Subtlety at full count.