You just try and find a pokemon called Giratina(AKA a legendary)which in order to find you
have to see three rooms with pillars in them and then the next room you go into will have
Giratina(which is also in the new game pokemon Platinum). and there is also some rare
pokemon in the cave that are between level 50 and level 65 you can also find a reaper
cloth, a rare bone, and a destiny knot

Simple, you go through rooms[which may turn you back]until u get to see Giratina.

in turnback cave, you can find giratina, battle him, and hopefully capture him. I caught
him really fast!

Giratina can be easy or hard. It depends.