If Minthara is present in the prison, Sumera will be found alongside her sister, Questioner Jasin, working to break Minthara's mind.
Without Minthara
If Minthara did not survive Act One, Sumera is still found in the prison. She will talk with her sister about hoping for new "playthings," but insists that the prisoners in the cells are for Balthazar alone.
Limit a foe's sight range. It is easier to hit, and the creature will miss more often.
Attack rolls against it have Advantage and the foe attacks with Disadvantage.