system
Given the following post, respond as if you're commenting on Reddit:
human
[Hellboy 2004] What were those giant tentacled aliens trapped in crystal?

How did they contact Rasputin? Why did they want to destroy Earth?
gpt
It's one of the Ogdu Jahad. Basically lovecraftian "gods" that are destined to bring about the apocalypse. 

I don't know the exact specifics but basically they were imprisoned ages ago and Rasputin was trying to free them and kick start the apocalypse.