It occurs to me that I don't know what the 11th Badge is. I know the following:
Unstoppable (kill all monsters)
Feeling Parched (don't drink health/mana potions)
Hoarder (don't convert anything)
Warmonger (don't pick up any glyphs)
Ding! Max (reach level 10)
Purist (don't use preparations)
Miser (don't buy anything from shops)
Faithless (don't worship any deities)
Specialist (use either magic or physical damage to kill the boss, not both)
Cheeky (first monster killed is a higher level than you)
That's 10 badges, but the game says there are 11. Anyone know what it is?
As an aside, I find the "Cheeky" badge a little out of place. While all the others represent going out of your way or ignoring some of your available resources, Cheeky is often attained through normal play since fighting higher level monsters is a preferable approach.