When a nine-year-old, native American boy is struck by lightning and initiated to be the next tribal shaman, he must battle his vengeful Uncle who murdered his father, and protect the world from the dark forces that seek to destroy it.

Logline: “When a nine-year-old, native American boy is struck by lightning and initiated to be the next tribal shaman, he must battle his vengeful Uncle who murdered his father, and protect the world from the dark forces that seek to destroy it.” (41 words)

Try to keep loglines under 30 words. But, looking through your profile it does seem you’ve tried to address the feedback from previous versions. I suggest reading through other loglines and the feedback they receive to better understand the elements of a logline and their structure.
Breakdown:

Protagonist: “nine-year-old, native American boy” —> His age seems to have nothing to do with the story, so describing it only serves to take up space in the logline. What’s more important than specifying an age is describing the protagonist’s personality, or a physical trait which may hinder achieving the goal of the story and resolving the conflict. (ex: ‘na?ve’, ‘reckless’, etc..)

Antagonist: “his vengeful Uncle who murdered his father” —> This description raises more questions than it should. He’s vengeful, but the logline doesn’t describe what caused him to want vengeance. In fact, the logline describes a perfect reason why the?protagonist would be vengeful: the uncle killed his father. Is the uncle envious because he wants to be the shaman? Is that why he murdered the father?

Inciting incident: “When a nine-year-old, native American boy is struck by lightning and initiated to be the next tribal shaman”
and
Goal: “he must battle his vengeful Uncle who murdered his father, and protect the world from the dark forces that seek to destroy it.” —> The inciting incident should directly lead to protagonist pursuing the goal. Becoming a shaman is not an event which directly leads to the protagonist doing what is described as the goal. Also, the logline is a bit unclear. Is the protagonist’s goal to battle the uncle to protect the world? Or is the logline describing two separate goals? (It shouldn’t do that.)
Becoming a shaman is likely an event which throws the protagonist into his new world, but it doesn’t make him do anything. In the story, there’s likely an event after this, an event possibly caused by the uncle which makes the protagonist realize he has no choice but to enter this conflict.
Is the murder of the father in the story, or is it backstory?? This review is getting long, so I’ll refer you to a previous review of mine in which I discuss the inciting incident-goal relationship. (Linked —>here)

I’ll throw in an example of a logline using elements from the original post:?After his father is sacrificed, a young tribal shaman must use his newfound power to prevent his murderous uncle from completing a ritual to summon a mythical demon. (28 words, 166 characters).

I hope this helps. I do think the premise of the story sounds interesting — I’m always interested in stories about Native Americans.