Navigating the Cave
Turnback Cave is a randomly generated dungeon. Because the cave changes every time you enter, you will not be able to recognize the correct path to Giratina's room. One strategy is to walk north in every room and hope this progresses you forward. You can also use your own strategy to find Giratina.
Returning to the Cave
Once you have captured Giratina, you may return to the cave for a minigame of sorts. The goal is to travel through the cave and reach the final room, the room that previously contained Giratina, as quickly as possible. The dungeon is still randomly generated, so the prize you earn is based on luck.
Prizes
The quality and value of the prize you earn is based on how quickly you reach Giratina's room. If you reach the end by passing through only three rooms, you earn a Reaper Cloth. Giving this item to a Dusclops and trading it to another player will trigger Dusclops' evolution into a Dusknoir. It also sells for 1,050 pokedollars. A path through four to15 rooms gets you a Rare Bone, which sells to stores for 5,000 pokedollars. The prize for 16 to 30 rooms is a Stardust, which sells for 1,000 pokedollars.
Tips
Bring a Pokemon with the move Dig. That move will return you to the cave entrance after claiming your prize, allowing you to explore it again immediately. Teleport and Escape Ropes also work, but Teleport will return you to town. Don't worry about being stuck in the cave forever. If you have not reached the final room within 30 tries, the cave will eject you, and you can try again.