HITMAN 3

If you already finished the Berlin mission at least once you can follow the guide below using the "Club Entrance" as your starting location to knock out this achievement.
If you have NOT completed the mission so far, I'd recommend following the guide at Solution for Partied Out In HITMAN 3 for the "Partied Out" achievement first, since that guide also works when you are starting at the gas station.

Either start with a disguise or get a disguise to enter the club and head down to Hirschmuller's office. Use a distraction to take him out, hide his body, take his disguise, and pick up the numbers he drops. Use the phone in his office to call the ICA members to the office. Wait at the desk for 5 of them to come down and be identified. Then flip the table and kill them all. Your achievement or trophy will pop when you complete the level, pause and quit, reload a save, or die.