This dungeon is incredibly frustrating
Half way through the next dungeon, a cutscene occurs of Espeon and Umbreon finding a secret cavern. Inside this cavern, they find several cards for the entry gate, and a passed out Keldeo
Get to the top of the dungeon and Kyurem appears and you have to battle him
The battle is a bit different in that his moves are properly animated and give you a chance to attack. Defeat him and you can follow the path behind, but he gives you warnings about what's back there before you do
At the top, you will find a Crystalline Entity emmanating the weird forces that have been manipulating Kyurem and the other Pokémon. This force tries to incapacitate you, but the hopes of the Pokémon around you give you the power to go on.
With moves having no effect, things look grim. You manage to bring enough strength to crack the entity, stopping the aura from spreading around the world...but it suddenly relapses
Arriving in town, everyone goes to greet you and Dunsparce appears to take you to see the rainbows where the palace once stood. When there, the ghost of Hydreigon appears