Need help remembering the name of this anime movie

[Signacat]

Hey guys,

There was an anime movie that played on TV in the US somewhere between the late 80s and early 90s. I only remember a few things about it so I hope the details are enough.

At the end the bad guy fall and is impaled on a spike, I believe it was a tall spike on a castle. There was another part earlier where a little girl/boy (unsure which, but he/she was the protagonist I think) is in a tunnel (I think in the side of a mountain, but the walls were made of rock) and this creature or mechanical thing is rushing down the tunnel yelling "Aaaaaaaaah" in a way that sounds like you made it in the very back of your throat.

That's all I can remember but I must find this anime and watch it again. Any help would be appreciated.