Arms of Hadar sweeps their wide board of small white creatures (Novice Inspector, Thraben Inspector, Raffine's Informant, and Battle Screech's 1/1 Bird tokens all die to -2/-2; Fortress Kin-Guard only dies if they choose the Spirit token with endure, since a +1/+1 counter makes it a 2/3 that survives as a 0/1), which is crucial since Mono-White Aggro wins by swarming with cheap bodies and pumping with Ramosian Rally. Murmuring Mystic is too slow to impact the board in time against this aggressive curve, so it can be cut for a sweeper. Keep Dispatch to tap down their bigger threats like Leonardo, Big Brother or Search Party Captain, and it exiles them once you have three or more artifacts for metalcraft. Lean on Baleful Strix and Refurbished Familiar for efficient blockers. Prioritize stabilizing the board state before they accumulate too much battlefield presence.