Revised (Round 2)- After a tragedy in London, Ohio, sends a dead soldier to the Veil World of the Supernatural, The soldier must stop a werewolf from entering the veil and destroying reality and exposing the supernatural to world, provoking chaos and destruction.

If the soldier was transported to the veil world it would have to already be open, therefore, the warewolf doesn't need to open anything - it's already been done. OR am I missing something... Did the soldier find another way into the veil world? Sorry, I can't seem to get my head around the mechanisms at play.

About this re-write, It is still missing cause and effect; as in... Cause: When this event happens, Effect: The lead character must accomplish this.

In your logline, you have written the cause as; the lead character is transported to the veil world.
This leads to the effect, he must stop the werewolf.

However one doesn't actually cause the other, the lead character could be transported to the veil world and not try to stop the werewolf.
Why must The lead character, have to be the one to stop the werewolf? You haven't personalized this logline. Why him?

Why not some other warrior? What event causes the lead character to get personally involved?

What's the veil world? If you're creating a fantasy world and with fantasy locations, you have to make sure that the reader understands what it is. Imagine if you didn't know what Rivendell was and someone included it in a logline. You might have to use more words but I think that's par for the course with fantasy loglines, there's a world to introduce - not just a story.

His only characteristic is that he's relentless. What his emotional journey? Why must he be the one to stop this happening? Why not another guy? As Craig pointed out, a fighter just fights. Is he actually a warrior? A hero? A wizard who fight with magic? Give us a little more to understand who this character is.

Destroying reality is one of those goals that is so finite it's completely non-sensical. It's like destroying the universe. What does the werewolf have to gain by doing this because, if he's destroying reality, surely he's destroying himself? If you mean "the real-world" as opposed to "The Veiled World" then you need to be more specific.

There's a lot of confusing elements in this logline and it's never a good idea to allow the reader to try and work out what they think is going on.