What if we tried to create a movie script together!

Not far from Glenge, there were evergreen and beautiful elven forests.

"evergreen" together

By a strange coincidence, it was through these lands that Albin's path led, right to the Grove where he was headed and where Hilael ruled.

Correct me if I'm wrong, but it seems to me that if it "led through," it should be "through these," not "in these." Or "through them"... You could also write "lay" or "led"...

Everything that grows on the earth is sacred to the elves.

"that grows on the earth" separated by commas

They are sure that the elven race will exist as long as at least one unicorn lives, and therefore, the killing of a unicorn, elves consider the most terrible crime against their people and their goddess, Silanna.

Bring "killing" closer to "therefore" so there is no break...

Both of them wore long black cloaks, which would help their undead masters hide in the night.

masters

The others had to be constantly on guard when fighting these undead warriors.

warriors

And then Silberna realized that the magical ring on the finger of one of the vampires blocked the magic of the tree. And the vampires stubbornly climbed up to his palace.

Um... In the first sentence, "the ring blocked the magic of the tree," and in the second, "they climbed up to his palace"... Logically, it turns out that the vampires were climbing to the palace of the tree, because there is no mention of Hilael in the previous sentence... It needs to be changed to "to the palace of the High Elf" or Hilael or the High Druid or something like that...

When he jumped onto the platform, the battle was already in full swing.

"in full swing" together

He drew his dagger and thrust the hilt into the dead body of the vampire and, firmly grasping it , fell down with him.

add commas where indicated...

The second one was quite enraged that he could not reach his intended target because of some blade dancer. He sharply stepped back from him, grabbed an archer, broke his bow, and began to drink his blood.

Drinking blood from a body is not the same as drinking from a cup. You can't do it in half a second. Do you have any younger siblings? In any case, if possible, get a pacifier and a baby bottle somewhere - try to drink at least half a bottle and check how long it takes. Divide the result by half - as if vampires are more skilled and faster in this matter... In any case, it will not take less than 30 seconds. I think so. And even in 5-10 seconds, Silberna can quite realistically jump up and strike... He simply could not stand there all the time and wait for the vampire to finish drinking...
It is another matter that the vampire could become invulnerable while drinking, like a Blood Drake... In short, Silberna should definitely have struck the vampire while he was taking a sip of fresh blood... He could strike and be surprised that the vampire's blow seems to have no effect on him - for example, the wound begins to heal right before his eyes... And then the vampire breaks away from the victim and knocks Silberna down with the hilt, who is staring in surprise at how quickly the wound from his blade heals on the vampire... Clear, right?

Below, already hearing the sound of falling bodies, alarmed elves gradually gathered, who realized that someone from the strangers had decided to break into Hilael's palace through the back entrance.

Well, let's say, the falling ones could be noticed even in flight. It's another matter that they could fall faster than anyone could realize... And "gradually" is generally a slow action. Guests can gather for a holiday gradually - some arrive at three, others at three-ten, others at three-forty, and gradually by four everyone has gathered...

That's all. I don't see any other mistakes for now.

Sincerely, Simas...