Having faced discrimination for being black in the past, 17-year-old Valerie Smol is intimidated to discover that she has telekinetic abilities and that she can use her newfound powers to defend the powerless. better, though I don't think the full connection is made b/w having faced discrimination and wanting to defend the powerless (BUT please wait and see if others say the same thing, I could be wrong)
When Valerie accidentally displays magic in front of her mother, she is shipped away to a secluded island full of witches being kept secret from the world. Valerie is abandoned to the mercy of those who run it. Downtrodden and alone, she is astonished when she meets Alex, a fellow magic user (wizard? that is traditionally the male user) and quickly develops an attraction to his nonchalant attitude about life on the island that seems to directly oppose her own. I like that you took my advice, but now that I'm reading it this clause seems to packed with information (sorry). Can you either shrink down the description of what he's nonchalant about or else change/shrink it to adjectives
When Alex contracts a murderous curse that brings itno apostrophes hostgiven the word "curse", "victim" is probably a better word than "host" here back from the dead with a hunger for flesh, Valerie is forced to search for a cure for the ailment because of the decisions of one of her past lives from centuries ago. Okay, so this is a paragraph with a wealth of important information. What I would suggest doing is changing the clause I underlined into one full sentence. Then take the remaining part of the sentence and expand on it - Valerie decides to search for the cure why, and explain to some degree about her past life (and if you can't do that concisely, you may have to cut it and come up with another *still accurate* explanation for why she must search for the cure
As the solution to the curse rests on one decision, Valerie must decide whether to end magic and save humanity by effectively destroying the magic behind the curse or saving magic and killing all of the undead. A choice that would be easy if her friends weren’t slowly joining the ranks of the undead.
Everything but the last two paragraphs are much better. And don't get me wrong, the final paragraphs are still good (they're nice and focused now). However, the stakes are still highly confusing. What I would suggest doing:
1) like I said before, change the clause I underlined into its own sentence
2) use a single sentence right after that to explain that Valerie decides to search for a cure because she cares about Alex (or something similar, if that totally isn't true. If it's more or less true, just say it. The query is short enough that it's allowed to be technically inaccurate - that is, nuanced issues can be simplified)
3) then expand the second paragraph to explain the decision she finds she must make... say she learns that she must do _____ to end the curse
4) use what she learned to define the stakes in the final paragraph (which is mostly done, but it will need slightly tailored to the choice that she has to make)
Let me ask you, how far into your story does this query currently go? That is, when in the story does she have to make this choice?