Mono Green Eldrazi is nearly identical to the Gruul Basking Broodscale build, ramping through Eldrazi Temple and Ugin's Labyrinth into Emrakul and other giant Eldrazi, so Damping Sphere disrupts their big mana-doubling turns and taxes multi-spell sequences. Dauthi Voidwalker races underneath their slow ramp plan while denying graveyard value, and Surgical Extraction can strip a copy of Emrakul or a key Malevolent Rumble hit. Force of Despair is too narrow against threats that aren't all cast the same turn, and March of Wretched Sorrow is clunky against their huge, resilient bodies, so both are trimmed for faster, more proactive disruption.