This one may be the one that makes me not want to play any more. 4 Arcane Imps and 2 Frost Imps, a room with walls, broken terrain, and low walls that block movement but not ranged attacks. Frost Imps chain casting freeze spells that keep you from moving into melee range, they all have range 6 or range 8 magical attacks that can shoot across the map, and multiple runs, so even if you manage to evade or kill the frost imps and prevent the freeze spells, you can't keep close enough to kill anything without them dancing away. And if you manage to kill a couple and take up a defensive position, the AI will cheerfully do nothing -- not even move -- for 20 turns (I counted) waiting you out. Can't get in range to hit them with discard attacks, the mage can't go toe-to-toe, and the fighter gets chewed to bits moving one square per turn.