Mono Black Aggro floods the board with cheap efficient creatures like Forsaken Miner and Nighthowl Pursuer, so Sheltered by Ghosts answers their best threat while gaining us lifelink and ward to survive the early beatdown. Rest in Peace disrupts their Corpses of the Lost recursion loop and Forsaken Miner's graveyard return ability, denying repeated value. We cut Dyadrine, Esper Origins, and Shared Roots since they're too slow to matter against a fast, low-curve aggro deck; we need immediate interaction and stabilization instead.