Funny, but I actually don't think you gave me enough with this log line, and usually people have the opposite problem. First of all, call your character by her name. Second, maybe add a few more details about what this object tries to do in the story and what the MC must do to stop it.Good luck!
I agree with Authoress - she's right on the money.
Perhaps explaining how the MC unleashed the ancient and deadly obsession would add specificity to your logline.
I agree with Authoress and the others. I'm also not clear about what you mean by "ancient and deadly obsession" - do you mean an ancient and deadly creature who is obsessed with something? I think you could clear this up with a few more specifics. Good luck.