Favorite Dark Sun Game Mechanic

The 4th day of #30DaysofDarkSun is here and the question is "What is your Favorite Dark Sun Mechanic?".

I really liked the Dehydration/Alignment mechanic from the original Dark Sun boxed set. It was one of the first examples in my experience that showed that alignments were a static trait. The fact that a Lawful Good character could temporarily change their alignment due to a lack of water really pushed the survival aspects of the setting in my mind.

Robert Scwalb, designer for 4th edition Dark Sun and creator of Shadow of the Demon Lord, had this to say:Psionics, no doubt. I always liked psionics in D&D, but Dark Sun made them an integral part of the setting.