Careful Study could make a case for the poster child of Odyssey block. It saw years of play around the block's most noteworthy mechanics - in Threshold with Nimble Mongoose and Seton's Scout, Flashback with Deep Analysis and Roar of the Wurm or Madness with Basking Rootwalla and Arrogant Wurm. Those archetypes are mostly things of the past, but Careful Study is still out there supporting Reanimator and Dredge decks.