After being threatened by an unknown adversary, a vampire warlord if forced to move against his rivals else it would mean certain death for him and his kin.

Sorry if the following happens to repeat feedback you've already gotten - I didn't read through all the notes posted to this thread.

As a rule of thumb, Loglines are best constructed using the least amount of absolutely clear detail. Most working decision makers will have multiple loglines thrown at them every week. If they can't immediately understand your story, they'll shut down and won't waste time/energy on absorbing any more information.

Going off your Revision 2, the logline raises more questions than it answers. For example:
- "...blessed champions..." is unclear; what are they the champions of? In what way are they blessed? Blessed by whom?
- If the MC is a vampire and he's fighting the vampire counts, how is he uniting his kin if he's also fighting them?
- Who precisely is he trying to usurp? All the counts? Just a few leaders? Usually, usurping is done to gain control over a single seat of power, whereas here it's implied that one character will try to take over several. This sounds like less of an attempt to usurp and more of an attempt to overthrow the ruling class by one person to gain power - in other words, a dictatorship. Think about pretty much any dictatorship throughout history - they all thought they were doing the best thing for the people, but how did that work out...?

Producers may or may not take issue with the above, but the fact is that these are legitimate questions, which require clarification. If you end up explaining such complex details (in a pitch) to producers, you can bet on them switching off and likely passing on the concept.

"In the novel"

Is this an adaptation of a published work?

"?However, from his point of view, he is not acting our of interest of building military might, but out of the belief that if his kin can't unify themselves, then they would all be wiped out. "

From my understanding, his plan is get all the other vampires to stop bickering or slacking off or what not, so they'll be able to resist a common enemy. So then, if he's intending to kill off the current leadership, is he planning on stepping up to the task? Unify his kind under himself?
Basically, what does unify describe? So it's not to build an army, but just so they can defend themselves?
Right now, I think what you're describing is -- as Richiev mentioned earlier -- too reactive and not proactive. The description in your comment sounds more like the point of "unify his kin" is to 'survive' more than 'defeat'.

Anyway, to throw out an example:?After a legion of blessed champions massacres his army, a vampire warlord must usurp the vampire nobility to unite the vampire factions to defeat this new enemy. (27 words)

Because if you say 'kin', I don't immediately think of?all vampires(or at least all of the ones in whatever area this is set in), which seems to be what you mean. I think of it more like a single clan or faction, which is fractured, and not multiple factions which are opposed and in their current state wouldn't be able to defend against an external threat.?

"After a legion of blessed champions massacres his army, a vampire warlord must usurp the vampire counts and unite his kin to defeat this new enemy." (26 words)

I suggest changing 'counts' to 'nobles'. While it is an accurate description, when I read the first version that used it I thought you may have meant 'courts'.

I think as is, "usurp the vampire counts" is too disconnected from "unite his kin". What is the ultimate plan of action? I assume it's to raise a fighting force. So how does usurping the vampire counts lead to the unification of his kin?
To point back to my example, I said "a vampire warlord must usurp the vampire counts in order to take control of their armies".

In my version, usurping the vampire counts is what leads to him gaining his fighting force - he takes control of their armies, that's the purpose of the action. It's a single plan of attack, both actions to accomplish his goal: defeat the enemy.

So, my advice is to connect the two actions, or delete one from the logline.