Shang Tsung has a curse to age incredibly quickly and die early, so he must absorb the souls of others to survive , thus gaining their powers and abilities. This curse that turned into a weapon was given to him by the Elder Gods for cheating in the Mortal Kombat tournament.
But I want to know how you can cheat in a competition that allows you to use magic, weapons, and kill your opponents.
What did he do?
According to the Mortal Kombat comics, Shang Tsung initially angered the Elder Gods by stealing the soul of an opponent he had defeated. Apparently, necromancy is something the gods frown upon, and was thus forbidden at the tournament. Tsung knew this, but did it anyway in his arrogance, most likely believing that the Elder Gods would not intervene. He was proven wrong.
You can read more about Shang Tsung's pre-reboot history here.
