“A lightning strike changes the half breed twins path as they search for the truth behind their father’s death. While a vengeful Uncle strives to strip their shaman grandfather of all that he holds dear.”
You seem to have three separate elements in your logline.
1: The investigation into the lead character’s father’s death, this seems to be the main story because it actually involves your lead characters: the lead character’s father dies mysteriously, which sets the course of actions for the twins. They decide to investigate.
2: An uncle that wants to strip the grandfather of all he holds dear. A: Since the reader has no idea what the grandfather holds dear; a cat? a favorite T-shirt? Old love letters?– this comes across as vague. B: Plus it doesn’t involve your lead characters so I would not include this B story scenario in the logline.
3: A lightning strike. Since we have no idea what this is all about I would drop this element or show in the logline how a lightning strike is relevant to the main story.
As a result, I would drop the lighting and the grandfather’s storyline from the logline. Because none of those things seems to have any relation to the main story of finding out what happened to the father.
I agree with Richiev. I would also suggest not using vague language like “changes the half breed twins path”
1. the logline doesn’t suggest to the reader that being a “half breed” is important to the story. The logline needs more context to make it important.
2. we don’t know what their original “path” was, so when it’s “changed” it doesn’t mean anything because we have no reference point
I agree with the above.
Also, take care of your syntax and grammar. You are a writer; delivering a couple of sentences in good shape is the least you can do. For example:
While a vengeful Uncle strives to strip their shaman grandfather of all that he holds dear.
A “while” clause needs a main clause. Check this out.
half breed twins path
My (Apple) dictionary declares “half-breed” (with a hyphen) as “offensive.” Also, since we neither know the two races that have come together to create the twins (they could be orcs and elves for all I know), nor the meaning of race in the world of your story, perhaps you should keep it out of the logline.