Hey, I discovered something new today.
When you are in the last room (near to 52XP) and if you have no more enemies to kill, the game doesn't allow you to escape the room even if you use all the potions and shield in it.
Let's see :
Last room :
After I select all the cards, the game is not finished (and if I press "Run" nothing happen)
EDIT1: Had the same bug, with 2 cards only and select the shield at the end.
EDIT2 : I can have "Completed dungeon !" message when I chose a potion at the end. So it seems to be a "last shield selected in last room" bug here :)