Wow, I should read the comments *before* I evaluating next time. Others already flagged the important points. We are of hive mind, it seems. And that's a good thing.
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Unusual to include a protag name unless the person is a known or historical figure and including the name is required to properly frame the LL.
Yours is a busy LL that pushed in several directions at once -- which can be anathema to LL clarity. If you had no choice but to keep only one through-line, which is it? The sociopathic son? The rivals jockeying for power? Or the alien empire about to start an interstellar war? Lead with one and hint at the others, if the subplots absolutely have to be there -- and usually they don't. For me, the son (intimate, personal) and the alien empire (vast conflict, unimaginable consequences) are candidates.
So, I'd distill it to:
"A dying galactic ruler struggles to control his crumbling empire and avoid interstellar war while his lunatic son plots against him."
The core conflict would seem to be the emperor and his power-hungry son. The emperor can achieve nothing while his son undermines his every move. The son is a constant distraction sapping his focus and strength.
"Struggles to control" (and the original "struggles to maintain") is far too vague for my liking. It's not a clear-cut yardstick. Here, "control" is a slippery thing that comes and goes in arbitrary units. It's sort of open ended. And that's a problem for a protagonist goal. Gotta be able to gauge progress towards the goal, which gives a sense of forward movement (or backward).
I'm wondering if the conniving son is working from within or without. Are they far apart emotionally and geographically, their armies clashing and skirmishing as the son presses to take back his home city? Or are they under the same roof still, the son outwardly, dutifully at his father's side while inwardly orchestrating the plot to usurp the throne? We don't know from the logline if the emperor knows of his son's machinations. Clarifying that clarifies the LL and imbues it with specific motivation:
"A dying galactic ruler struggles to make peace with his power-hungry, traitorous son when their torn and crumbling empire faces interstellar war."
There's no doubt remaining in that revision: the two are at each other's throats, but the father still believes they can reconcile.
I'm probably highlighting elements other than those you intended. But you can see how this example gives the reader a clearer indication about the protag's plans to solve his problem: he'll try to make his son see reason; he'll work to rekindle the father-son bond -- rather than just "struggling to maintain control" generally.
Cheers,
pitchpatch, 10ptt.com