ROWAN of the Sindari warrior clan has been wandering in self-imposed exile, his guilt at a failed attempt to save his sister’s life throwing him into self-destructive behavior. Rowan returns to his home realm six years away [Six years away? Meaning it will take him six years to get there? Change "six years" to a measure of distance. Or say "six years after leaving," if that's correct.] to find that the realm is holding trials and an election for the next king. [Why is he returning home if he didn't already know about the trials?] As a possible claimant to the crown, Rowan’s father entreats him to journey to the capital [This reads like Rowan's father is the possible claimant. Rowan is urged by his father.] and take the trials. [I would go with "enter" the trials or "compete in" the trials. "Take" doesn't seem like the right word.] Seeing a chance to redeem himself of his failures, Rowan agrees.
To cross the desert wasteland, [He returned to his home realm in the previous paragraph. Why is he crossing a desert now? Is this part of the trials?] Rowan enlists the help of his unknown cousin, BRYND, a young thief buried in debt to a crooked magistrate. [His cousin is unknown? What does that mean?] During [a] skirmish [with ?] , a bearded stranger aids the company. Wary of letting any strangers join them, Rowan reluctantly agrees to let him join - only to later discover the stranger is a young woman KIVRIN desperate for help crossing the mountains. Furious at her duplicity, it is only by [at] his men’s insistence that he allows her to remain.
Being the only strangers in a company of men who have known each other for years, Brynd and Kivrin become instant friendship. [They become friendship? Either English isn't your 1st language, or you didn't read this very carefully.] Kivrin’s quick-thinking saves Rowan’s life, [Why was his life in danger?] and Rowan agrees to help her learn how to handle a sword as well as she handles knives and a bow. Brynd joins them and the three form a fierce bond.
The company is attacked by the skcree, lizard-like humanoids, and are taken before the skcree overlord, where the company is shocked to discover Kivrin had been held prisoner there before. In an attempt to free her friends, Kivrin pushes the overlord over the edge of a ravine but falls with him. The company flees only to be trapped on the mountain’s edge. Kivrin survives her fall and races toward her companions. She sees the SANGUIS, the demon who killed Rowan’s sister and later imprisoned Kivrin. Rowan attacks the Sanguis but is defeated. Kivrin unwittingly summons dragons to save him. [If you do something unwittingly, you don't even realize you're doing it. Thus you don't have a reason for doing it. So either delete "unwittingly" or "to save him."] The dragons bear the company away, not knowing Kivrin survived. [This reads like the dragons don't know Kivrin survived. They must know she survived, as she summoned them. Do you mean the company don't know she survived?] She awakens alone and speaks with a dragon who returned. Before Kivrin can escape, [From what?] she’s shot with a poisoned arrow. The dragon takes her to find the company, not knowing they had already moved on.
The Sanguis reports to his master, THE PALE PRINCE, that his prize has fled. The Pale Prince orders the skcree to find her, with the words “I want my witch back.”
[That's the end?]
Presumably this trip across the desert is Rowan's trip home. So start with his decision to cross the desert and go home, not with his arrival at his home.
If your world has talking dragons and lizard-like humanoids and a demon, that probably gets mentioned early on, and should also be mentioned earlier than paragraph 4 in the synopsis.
You spend a lot of time on that long paragraph, but it comes across as a list of events without much elaboration on any of them. You don't have room to get that specific about one or two chapters.
I would change the word skcree to either Skree or Scree.