Dimir Midrange has a deep interaction suite of Counterspell, Force of Negation, Thoughtseize, and Fatal Push alongside Orcish Bowmasters and Psychic Frog as value threats; Thoughtseize lets us proactively strip their best counterspell or removal spell before deploying our own threats, playing around their disruption. Claim the Firstborn can steal an early Psychic Frog or Orcish Bowmasters token before it snowballs into card advantage. Nethergoyf and Ox of Agonas come out since they're both clunky against a deck full of cheap efficient removal (Fatal Push, Preordain-fueled interaction) and hard counters that punish big, telegraphed spells.