The Shining Silver Crystal: The Moon Princess Appears Episode 34

Zoisite tracks down Mamoru and challenges him to a duel where winner takes all of the Rainbow Crystals. Mamoru is heading to duel when he runs into Usagi. She notices his bleeding shoulder and follows him. When they arrive, Zoisite tricks Mamoru into laying down his crystals and Kunzite appears and takes them all. Then Mamoru and Usagi get trapped in the elevator of a crumbling building, and they are both forced to transform (and reveal their identities to each other) in order to save themselves. They find themselves transported to the Dark Kingdom. Zoisite attacks Sailor Moon with a shard, but Tuxedo Mask takes the blow instead. When she sees Tuxedo Mask wounded, Sailor Moon cries. Her tears call all of the Rainbow crystals to her and they form the Silver Crystal. The crystal takes its place on the Moon Stick and Sailor Moon is now transformed into Princess Serenity.