Spelling and Grammar: Your grammar wasn't that bad. You just made common mistakes that everybody makes. You switched up to and too. Here's an example of both:

To: I went to the broke down store down the street.
Too: There was too much people who walked too slow, rather than fast.

That's what they are supposed to be used for. Do you see the difference? Your spelling wasn't too bad. There was only a couple here and there, but that happens to everybody.

Plot and Story Line: I really like your plot. I really enjoy the Percy Jackson books and I enjoyed reading this. It's different and unique. I liked how you put some twists here and there so it wouldn't be identical to the book. You are a really great writer and I can't wait to read more from you.

I would give this story a 8/10.

Notes

If I was a bit offensive, please tell me and I'll take your review down. I'm just being honest and giving you tips on what to do and what not to do. I'm trying to help you improve and that's my main goal of doing reviews. I'm not trying to be mean in anyway.