buzz assassin 

One who would go proactively go out of their way to kill your buzz. The violence and glee with which they go about this task puts them at the level of assassin ... a buzz assassin.

I avoid going to Monday's before 4pm because the buzz assassin that runs that place in the afternoon won't serve me more than 2 drinks before shutting me off.

buzz assassin by Mr. Dyche March 12, 2018