As DM...
131) I am not allowed to try to make the party run away, not even from a force obviously and mind-bogglingly superior to them. No matter what I do or say, the party will assume they can take it.
132) I am not allowed to start combat from 2 miles away, even if the enemy gets a shot at the PC's every other round while they close.
133) My BBEG is not allowed to cast one or two spells from the back of a group of mobs, then run away cackling, only to repeat the process three, four, five times.
134) I am not allowed to have the party start in a tavern. Or prison.