The 2 Most Diffucult Rooms are 4 and 5
• 4th Room is tricky, I personally let the assassin swipe his sword at me when hes really close up
Then go for it
• 5th Room is all about Patience, Accuracy, and Timing... for the assassin going up the stairs.
• Really you want to find the EXACT SPOT to aim in this video
.Here's a Visual for this achievement
, although he got lucky in room 4... feel free to use the up close method.