Dismember is efficient, cheap removal for their small mana dorks like Llanowar Elves, Elvish Mystic, and Fyndhorn Elves, slowing their Gaea's Cradle-fueled ramp into Craterhoof Behemoth. Mycosynth Lattice turns every permanent into an artifact, which lets our own artifact synergies and interaction broaden dramatically, though be aware it also helps them if they have artifact synergies (they don't in this list, so it's safe). Eldrazi Confluence is clunky against their low-curve elf swarm, so we trim it for cheaper, more efficient interaction. Race is key: assemble The One Ring or Urza's Saga quickly since Craterhoof Behemoth and Natural Order can end the game abruptly once they hit critical mass.