Sending a Bulete against a Second Level party was one of my first experiences as a DM. I wanted to do something new and introduce a monster we had not encountered before. Back in those early days, we took turns being DM. Needless to say people did not want me to DM for a while after that.

What is funny in retrospect is that the party actually stood their ground and tried to fight the thing. I believe it was a TPK, but a do-over was called, and all those characters were available for the next session with a different DM.