Dimir Aggro is full of cheap creatures (Faerie Miscreant, Moon-Circuit Hacker) and discard/removal, and Arasta of the Endless Web gives you a sturdy reach blocker while punishing their Thoughtseize and removal spells with free Spider tokens. The Stone Brain can strip a key copy of Sheoldred, the Apocalypse or Kaito, Bane of Nightmares from their deck entirely, which is huge against a deck that leans on a small number of impactful cards. Ulvenwald Oddity is a lower-impact body against a deck full of efficient removal, so it comes out. Keep your ramp core since Dimir Aggro struggles to beat a resolved Cavalier of Thorns or Storm the Festival into multiple threats.