Translation help

onethirtyseven #1897
onethirtyseven has redacted their comment.
Aldaleon #1898

I'm not quite sure what they're trying to convey with this particular sentence, but deciphering poorly authored Elvish isn't a strength of mine!

"It will possess/refuse yourself and darkness on us, Taur-nu-Fuin[1] alone."

1. Forest under Night, a place name.

Does anyone else have any ideas?