Giant Chasm Kyurem .

It generates a powerful, freezing energy inside itself, but its body became frozen when the energy leaked out.

In Pokémon Black & White, when the player reaches the pond in the center of the Giant Chasm,
it starts snowing and the whole area will be buried deep in snow. This gives players access to the cave that holds Kyurem, at level 75.

In Pokémon Black 2 & White 2, Kyurem is only able to be encountered after the player obtains Dark Stone/Light Stone from N,
AND capturing the revived legendary Zekrom/Reshiram associated with the stones. Kyurem is encountered at level 70.