The Cursed Kill room comes with 7 sinful masks to collect. To get a mask you need to open some safes first so get cracking.
I already played the new Cursed Kill Room Heist plenty of times:
We are releasing the Cursed Kill Room a limited time event heist. During the next two weeks you can go in and crack open as many safes as you can. The timer only counts down when you are not protecting a safe, so be fast when securing the loot. You can gain extra time by shooting cops.
Do I need to open the safes from this new heist? Or are they talking about the usual safes that drop randomly once per week?
Just got my first mask and this is what you need to do:
Play the Cursed Kill Room heist (on any difficulty) and open 4 safes.
When you run back to the start, where you then have to press the button to end the heist, stop in the long hallway right before you get back to the room you started in. On the left wall, you will see this:
Press the button of the mask you want, wait a few seconds until it materializes and then take the mask. (This last part is import, you need to take it, just pressing the button is not enough.)
As far as I can tell, you can do that on any difficulty and even see on the counter there how many safes you still need to crack. I did this solo with bots, it is enough time.