Survival Elves ramps with Birds of Paradise, Fyndhorn Elves, and Gaea's Cradle into a wide creature board backed by Survival of the Fittest tutoring, so we want disruption to their mana engine and protection for our own development. Xantid Swarm's attack trigger denies them a turn of Survival of the Fittest activations or Swords to Plowshares on our key permanents. Tormod's Crypt can strip Squee, Goblin Nabob and other graveyard value tied to their creature recursion plan, and Ray of Revelation cheaply answers an Armageddon-adjacent lock or any problematic enchantment they bring in. Parallax Wave is a poor rate against their go-wide, low-power creature swarm since fading limits how many creatures we can lock away, so it's cut; note we are trimming only one copy of Sterling Grove and Opalescence (not the full playset) to preserve our core engine's redundancy.