this story describes perfectly why extended crit charts make gaming completely unhinged:
http://www.tabletitans.com/tales/post/a-beer-to-die-for
Also, Table Titans is a really good D&D comic...
Now that's one beer he'll never forget!!
Haha. I wonder what you do as a DM to make up for that. Throw your hands up and storm out? Pretend it wasn't the /actual/ evil wizard? Retcon the whole thing such that there's a new boss?
Yeah, I really don't know. I mean, there was a fair bit of prep work done, but at the same time the group had agreed to use the extended crit tables...
Oh hey, maybe just make it so the players are going to clean up the mess the new power vacuum has created :D