This matchup is a race against a turn-one Phyrexian Dreadnought backed by a dense wall of free and cheap interaction like Stifle, Daze, Counterspell, and Foil. Xantid Swarm flies in, and the moment it attacks, the opponent can't cast spells for the rest of that turn. That gives you a clean window to activate Hermit Druid and resolve your combo pieces without fear of a counterspell or a Stifle. Swarm needs to survive a turn to be able to attack, so deploy it early and bait out a counter if you can. Elvish Spirit Guide is a weak cut since its mana acceleration matters less than having a way through the counterspell wall. Keep the core combo intact and prioritize finding a turn where you can attack with Xantid Swarm before going off.