Return to Route 214 and head through the special passageway that will take you back to Sendoff Spring. Now that Cynthia is gone it is time to enter Turnback Cave.
Use Defog to remove the fog and read the pillar that says "...Past three pillars...offer up... to the... ...before 30 is surpassed...". It means that you must find 3 pillars while going through the rooms before you go through 30 rooms to reach the room where the portal to the Distortion World is, otherwise you will have to start over from the beginning. For the room filled with smashable rocks you need to investigate their formation and figure which door to take, the western, northern, or eastern door out of the four doors. The further you go down the stronger the wild Pokémon will be.
A colored background means that the Pokémon can be found in this location in the specified game. A white background with a colored letter means that the Pokémon cannot be found here.
A colored background means that the Pokémon can be found in this location in the specified game. A white background with a colored letter means that the Pokémon cannot be found here.
A colored background means that the Pokémon can be found in this location in the specified game. A white background with a colored letter means that the Pokémon cannot be found here.
A colored background means that the Pokémon can be found in this location in the specified game. A white background with a colored letter means that the Pokémon cannot be found here.
A colored background means that the Pokémon can be found in this location in the specified game. A white background with a colored letter means that the Pokémon cannot be found here.
A colored background means that the Pokémon can be found in this location in the specified game. A white background with a colored letter means that the Pokémon cannot be found here.
A colored background means that the Pokémon can be found in this location in the specified game. A white background with a colored letter means that the Pokémon cannot be found here.
Once you've gotten past the three pillars and got whichever item was waiting for you, you'll find the room with the portal to the Distortion World. If you failed to catch Giratina last time you'll find it guarding the portal to which you must face, this time in its Altered Forme.
One slight advantage if you decided to KO Giratina in the Distortion World earlier and face it again in this rematch is that in Altered Forme it prioritizes defenses over offense, so its attacks are not as strong compared to Origin Forme. Its moveset is still the same though. Just use the same tactics as last time and SAVE before facing it, otherwise you'll have to defeat the Elite Four again to get another chance to catch it.
When ready use the portal to return to the Distortion World.
This time around you do not have to worry about getting lost. Follow the path until you find the Griseous Orb. The Griseous Orb when held by Giratina will allow it to maintain it's Origin Forme outside of the Distortion World.
Canalave City
Your next destination is Canalave City. Head to the small house on the southwestern area. Go inside and you'll find a boy that is having a nightmare and talk to the mother and you'll learn that you need to find an item called the Lunar Wing on Fullmoon Island to treat her son. Go and talk to the sailor who mans the ferry Sailor Eldritch who happens to be the boy's father and he'll happily take you to Fullmoon Island to find the Lunar Wing to treat his son.
Follow the path and head into the inner sanctum where Cresselia is. When you interact with it, it will flee, but it leaves the Lunar Wing behind. Return to Eldritch and have him take you back to Canalave City. Return to Eldritch's house and use the Lunar Wing to heal his son from his nightmare. As for Cresselia similar to Mesprit, Zapdos, Articuno, and Moltres it is roaming around the Sinnoh region so you need to use the Marking Map to track it.