The Assassin’s Promise by Merri Bright

She was bred to be lovely. She turned out lethal.

After escaping an evil king bent on reviving an extinct, magical line, Roya promised to dedicate her life to ridding the world of abusive tyrants. But when her mentor, Thorn, flunks her out of the Assassins Guild, she flees her humiliation and runs straight into danger.
Now kings and warlords hunt her, somehow privy to her deepest secret—that she is one of the legendary line. Thorn is her only ally, until Roya’s magical lure inadvertently draws more than one dangerous protector to her side.
Roya wants to be known for her skills as a poisoner, not mysterious powers. But when Thorn teams up with a prince, a warrior-scholar, and a pirate, there may not be enough poison in the world to kill the pull she feels to all four, though these men may not be who they say they are. And some may want to lock her away for themselves.
Maybe it’s time for her to cook up a deadly plan of her own.