On turn one, this can give the acceleration of a Llanowar Elves by getting a Dryad Arbor. On later turns, it can get a large creature or a one-of "toolbox" creature such as Gaddock Teeg. While this is interesting, it is also too efficient. If one intends to build a deck that has turn-one accelerants, Green Sun's Zenith is a great choice. If one wants to more access to utility green creatures, Green Sun's Zenith is a great choice. If one wants to more reliably get a large green creature, such as a Primeval Titan, onto the battlefield, Green Sun's Zenith is a great choice. However, this ends up with fewer different decks being played in practice, as Green Sun's Zenith is such a good choice that there are fewer green decks that do anything else. The DCI hopes that banning Green Sun's Zenith increases diversity among Modern green decks.