Dimir Self-Bounce leans on tempo plays like Momentum Breaker, Nowhere to Run, and their own Boomerang Basics to disrupt your board, so countering their key spells with Spell Pierce and Spider-Sense before they resolve is more valuable than reactive removal. Their creatures (Fear of Isolation, Cryogen Relic-backed plans) are generally small, so cutting a copy of Burst Lightning for more interaction is fine while keeping enough removal for Fear of Isolation. Boomerang Basics is redundant against a deck already trying to bounce your stuff and doesn't answer their Thoughtseize-backed disruption plan. Play proactively and use your own countermagic to protect key threats from Nowhere to Run, since they have very few ways to deal with a resolved prowess creature otherwise.