For every Missouri Repertory Theatre import that managed to disappoint during the past year (such as It Ain't Nothin' but the Blues), another made a strong impression -- perhaps none as much as Metamorphoses in January. Creator Mary Zimmerman's stroke of genius was to set Ovid's versions of familiar Greek myths in and around a 20-foot-by-30-foot pool, ankle deep at one end and nearly knee-high at the other. What could be more apt for retelling stories about Narcissus or Poseidon? Even the tales that didn't require water, like that of King Midas, delivered electrifying results.