“ Rather than making a baddy impossible to hit, consider giving it mega-hit points.
Super hard to hit leads to great player frustration. Allowing them to do damage leads to a sense of accomplishment. another variation of this would be to give the bad guy a forcefield that shows damage.You could also give them a mastermind ability that sluffs the damage of to minions who should be easy to kill.Once in a while a super high to hit encounter is ok ,but it should be few and far between.
Your mileage may vary”
“ A local sculptor of note has chosen to honor the adventurers by crafting lifelike statues of them. While he hopes to surprise them by setting the statues up in their home while they are off adventuring, he may have underestimated the paranoia of the typical adventurer. Provided that he can get in, is he likely to survive whatever precautions they have against intruders? Assuming he lives, what will they make of finding statues in their house?”
“ An evil ruler got the idea of mixing a trampoline and a gallows together. As long as the one to be hanged bounces on the rubber trapdoor it won't open, but bouncing gets very tiring after a while.”