The new Rogues saying it's the normal craziness for a Wednesday reflects the fact that the show premieres on Wednesdays.
Khione appears to have powers related to life, based on the facts that she revitalized Mark and sensed the baby in Iris.
Red Death uses copies of her armor to take over, similar to how Batman cloned himself in "Return of the Caped Crusaders" after being turned evil and seeing how incompetent the GCPD was.
The title is a play on Edgar Allan Poe's 1842 short story "The Masque of the Red Death." Lines from this story were recited by Keith/Goldface in Rogues of War (2023).