One literary device that comes to mind is allusion. In her novel, Maryse Condé directly alludes to a famous literary character, Hester Prynne. In case you don’t know, Hester is the main character in Nathaniel Hawthorne’s novel The Scarlet Letter.
Like Tituba, Hester faced discrimination. However, Hester’s discrimination had less to do with skin color and witchcraft and more to do with gender. In both Hawthorne’s novel and Conde’s novel, Hester is punished because of adultery. The man is not in jail. Hester tells Tituba, “And while I am rotting here, the man who put this child in my womb is free to come and go as he pleases.”
You could say that the allusion to Hester and The Scarlet Letter helps magnify Tituba’s discrimination. It lets Conde highlight the multiple ways women of different colors could be mistreated. More so, you could argue that Tituba’s connection to Hester makes Tituba’s struggles seem more important or crucial, since she’s in the company of a famous protagonist from a canonized work of American literature.
You could also argue that irony is a literary device that Conde uses to highlight Tituba’s discrimination. You could say it’s ironic—that is to say, strange, paradoxical, or incongruous—that Tituba is jailed for doing something good. Remember, Tituba tries to help Parris’s wife and daughters. Her attempt to be a positive influence leads to punishment.
One more literary device is foreshadowing. You could claim that Tituba’s past experiences in Barbados help set up her New England fate. They show that discrimination and abusive treatment were a constant part of her life, not just something that happened to her one time in Salem.