Here's a cool way to enhance your player's fatality...Choose a stage with stage objects (Moloch's Lair, or Ice Stage for example). When it is time to finisher your opponent, position them near a stage object and do your finisher. If you have any luck, you will break the object as well.

The first one I did was when Scorpion threw his harpoon through a stone statue and into the opponent's head - it was very cool looking. Other fatalitys that I can think of that may work are: Sonya's Kiss, Kung Lao's Hat Throw, Cyrax, Jax, Lei Mei, Hsu Hao, and there's probably a few others as well.

Just a cool trick I discovered, enjoy!