This loophole will help you stay completely invisible to the guards, and kill silently. For this:
1) mingle with the crowd
2) invite friends
3) Let them go
4) Profit! Kill as much as you want and you will get nothing.
Hint: “Escort” opportunity opens with Assassin Jacob Zenger in New York.
Note: Incognito Mode can be disabled by crowd blending, desync or fast moving. Does not work on Frontier (Assassins cannot be summoned).