Unlike the Vaas Insanity DLC, I was able to attempt the Mind Level 5 after completing the first escape from Pagan's mind.
There are better powers available than in the 1st level, so doing the easy delusions for some powers can help you out.
Sound and Fury and House on Fire each give you 3, and Thicker than water gives you 1 (though if you chose Pagan, there is a power chest you can swing to)
If your still struggling, you can also go to System>Options>Gameplay and change the difficulty from action to story mode (all DLC starts on Action Mode by default)
For King and Country:
Only mask memory with a real boss, so I suggest doing this one first before the difficulty level ramps up.
Rewriting History:
The first time I burnt down the village for the Memory Rewriting History enemies would spawn every time I lit a house on fire. Every other time I sniped everyone in the village first and no one spawned until I burnt the final house and then you just have to kill the named "boss". Easiest to Snipe them if you come from the Sound and Fury as your in a location they can't reach.
Playing God
If you takeout everyone without being discovered no one will be spawned until the tower is fully created (then you get 1 named elite, and 2 normal enemies per level)
Night Time
You don't have a compass but if you go to System>Options>Audio>Subtitles> And turn on Sound Subtitles you will get a subtitle for "Ghost Charging" and the direction they are coming from.
I didn't see many of the powers as I skipped playing levels 2 - 4 but some that you should look out for:
Eye to Eye: Takedown alerted Foes
Unflinching: resist knockdown effects.
Contact High: heal on takedowns
Silent Killer: +damage with silent weapons
Hidden Hand: killing with silent weapon tags enemies
I also saw an extinguish flames when your on fire power, but I sold it because I wanted to keep my +respect ones at the time, so I'm not sure how useful it would be.
EDIT: stumbled across:
Toxic Temper Poison nearby enemies when you take damage
in safehouse before quiting. It's another very handy power to have, though it can interfere with takedowns.
"Secret" Ending
The "secret" ending is unlocked by completing Mind Level 5. You do not have to complete all the Waves, and you can skip the credits, and the tape recording ending will still play.