From describes it as “a high-difficulty challenge mode designed for seasoned players who have navigated through the Night many times.” There aren’t a lot of firm details right now, but the mode will include stronger enemies, weapons with “detrimental effects,” and a difficulty level that “increases the deeper you descend.” It sounds like there are five layers to work your way through, and if you make it through the first three, you’ll be treated to “an endless battle for those seeking even greater thrills.”
Sounds like just the thing for Nightreign sickos (complimentary) and it’s also launching pretty soon: “Deep of Night” will be available on September 11th.