things a DM can say that immediately instill fear:
-"okay... make a constitution save."
-"so several things happen at once..."
-"how many hit points do you have left?"
-"can I borrow some D8s?"
-"I'm gonna roll this one where you all can see it."
-"21 *doesn't* save, actually."
-"does a 33 hit your AC?"
-"can you make a perception check? ...okay yeah, you don't notice anything."
-"up next on initiative... something happens somewhere that you don't know. now, your turn!"