Genuinely the worst out of all the DLCs.
This has not been play tested.
Not thoroughly enough at least.
There are many bugs, there are many oversights, there are many clear and frustrating issues if you are planning on 100%ing this game.
I'll tell you right now, there are three achievements regarding this DLC that are notorious for being quite honestly some of the most devious and evil achievements I have ever had the displeasure of obtaining.
I kid you not, a great deal of playtime was sunk just to get these three achievements.
There is a saving grace for the "Run and Gun" achievements where you have to get only headshots without missing a shot, the last room has a wall with no collision in the bookshelf by the exit door.
And if you want the headshot to register on the last assassin climbing the staircase out the window, you have to aim above his head even though it makes no ♥♥♥♥♥♥♥ sense what so ever.
Sometimes the game freaks out and the staircase guy has no AI and stands still, but even if you hit him in the head in this state, it will not count. He has to be moving. This is also forgetting to mention the game can spawn two of each target for some ♥♥♥♥♥♥♥ reason or spawn so many assassins it crashes the ♥♥♥♥♥♥♥ game.

The other two I found to be incredibly painful, was the "By My Hand Alone" and the one with Slowed Time to get perfect scores on all stages including bonus ones.

Honestly if I knew about this before, I probably would've used it, because it genuinely isn't worth the RNG trial and error bullsh*t. Any achievement that's RNG ♥♥♥♥♥♥♥♥ with how physics props react to being in slow-mo or where enemies spawn, just don't bother with it. Install the cheat engine and just modify so you have infinite health and ammo. Spamming bolts in slow-mo will crash your game.

Every other stage and challenge, was fair. Challenging, which is the point, but fair. The RNG in those stages wasn't as nonsensical as those other achievements because you weren't required to keep a streak going or some sort of perfect record. I promise the other two DLC's are much nicer to play than this one. I promise the 2nd and DOTO installments are much more polished than this DLC is. You will have a more pleasant time playing other games in this series casually than you will pulling your hair out in what is honestly some of the most unfair gameplay I have ever played.

What infuriates me the most, is that there used to be cheese. And they patched it out. They made the already tedious bullsh*t more tedious and bullsh*t because you can't bypass a lot of it anymore. They kept the bookshelf in thankfully because I refuse to believe any of the devs beat that stage legitimately.

Genuinely the worst out of all the DLCs. This has not been play tested. Not thoroughly enough at least. There are many bugs, there are many oversights, there are many clear and frustrating issues if you are planning on 100%ing this game. I'll tell you right now, there are three achievements regarding this DLC that are notorious for being quite honestly some of the most devious and evil achievements I have ever had the displeasure of obtaining. I kid you not, a great deal of playtime was sunk just to get these three achievements. There is a saving grace for the "Run and Gun" achievements where you have to get only headshots without missing a shot, the last room has a wall with no collision in the bookshelf by the exit door. And if you want the headshot to register on the last assassin climbing the staircase out the window, you have to aim above his head even though it makes no fucking sense what so ever. Sometimes the game freaks out and the staircase guy has no AI and stands still, but even if you hit him in the head in this state, it will not count. He has to be moving. This is also forgetting to mention the game can spawn two of each target for some fucking reason or spawn so many assassins it crashes the fucking game. The other two I found to be incredibly painful, was the "By My Hand Alone" and the one with Slowed Time to get perfect scores on all stages including bonus ones. Honestly if I knew about this before, I probably would've used it, because it genuinely isn't worth the RNG trial and error bullsh*t. Any achievement that's RNG bullshit with how physics props react to being in slow-mo or where enemies spawn, just don't bother with it. Install the cheat engine and just modify so you have infinite health and ammo. Spamming bolts in slow-mo will crash your game. Every other stage and challenge, was fair. Challenging, which is the point, but fair. The RNG in those stages wasn't as nonsensical as those other achievements because you weren't required to keep a streak going or some sort of perfect record. I promise the other two DLC's are much nicer to play than this one. I promise the 2nd and DOTO installments are much more polished than this DLC is. You will have a more pleasant time playing other games in this series casually than you will pulling your hair out in what is honestly some of the most unfair gameplay I have ever played. What infuriates me the most, is that there used to be cheese. And they patched it out. They made the already tedious bullsh*t more tedious and bullsh*t because you can't bypass a lot of it anymore. They kept the bookshelf in thankfully because I refuse to believe any of the devs beat that stage legitimately.