Mishihari Lord
First Post
I would wager that your players are more upset about your use of invisibility than the actual TPK.
Look at it from their perspective. They're engaged in a fight with some enemies who they defeat. As soon as they win the battle, a more powerful foe instantly, magically appears and defeats them. *You* know that the monk leader was always there, but they don't. As far as they can tell, you pulled her out of your ass in an attempt to railroad the plot.
^Outstanding point.
First, find out why exactly they're mad. If it's what GSHamster's thinking, then show them the module and explain what happened. Or maybe there's something else. If it's just "I don't like to lose" then tell them to man up. (or woman up, as the case may be)