This mode is unlocked after completing a playthrough in Normal or Hard difficulty. This mode allows you to start the game with all the upgrades you unlocked in the previous game. You'll have to unlock some gadgets again, since they are given to you when you progress the story. This mode makes enemies stronger, faster and tougher, and the counter icons won't be displayed.

So for Combat encounters, evade a lot. Don't rely on counters because you'll barely have time to react when they attack you. Just jump over them and hit. And since you completed all the Combat challenges in Normal mode, you won't have to worry about defeating the enemies in a certain way. You can use the Special Combo Takedown and the Multi-Ground Takedown too to get rid of all the enemies faster.

For Predator encounters, avoid being seen at all costs. Enemies can kill you in 3 or 4 hits, especially if they have shotguns or sniper rifles. Take your time, be safe on vantage points and study the environment. Use this mode as a practice for I Am The Night mode, the next, harder mode. You can practice by getting used to restart the checkpoints when you are about to get killed or are discovered in Predator, you'll need to be fast with that in I Am The Night.