Tormod's Crypt exiles their graveyard before Hermit Druid mills their whole library into it, which directly disrupts their Volrath's Shapeshifter combo plan since Shapeshifter needs a creature card on top of the graveyard to function. Urza's Bauble is too slow and doesn't interact with their combo, so it comes out. Since this is a glass-cannon combo deck with very little removal or disruption of its own, our aggressive clock is also a real threat—try to kill them before they assemble Hermit Druid plus Shapeshifter, and use the Crypt proactively the turn before they're likely to go off rather than waiting to see Hermit Druid resolve.