Pokémon Diamond and Pearl/Turnback Cave

Turnback Cave is probably the hardest dungeon you have or ever will face. Inside are high level Pokémon, and the place is crawling with them. Also, you cannot use an Escape Rope to get out, so you will have to remember how to get out. This is way harder than it sounds because Turnback Cave is seemingly endless. Finding what you want here will be very hard. Before proceeding, use Defog to clear up everything and make looking around and battling much easier.

Pokémon Encounters
As you can see, the Pokémon here are very strong.

Points of Interest
Giratina is in a room after meeting 3 pillars inside of Turnback Cave. There are randomly-generated rooms inside of the Cave. They are all rooms with four doors to the north, south, east, and west. They either contain a pillar in the middle with a two number combination on them, or they contain patterns of Rock Smash-able rocks. You will probably want to bring a level 70 Pokémon with you, put in in the lead, and bring 15 Max repels along with you.
 * Giratina

To get to Giratina, you are supposed to pass three pillars before going through 30 rooms. The key is to finding an out-of-place rock in the formations, and go to a door near(or opposite?) it. However, there seems to be no solution for soultions with / /, \ \, < > patterns...but even if you come across these, do not go back the way you came, or you will end up at the beginning. Note the wild Pokemon increase in level every time you pass a pillar. However, in the entrance and rooms with a pillar, no wild Pokemon appear.

Note that whenever you come back after catching/defeating Giratina, after coming to the room where it once stood will get you an item, probably the Rare Bone. The inscription in the entrance of the cave also changes after your battle with Giratina.