Mortal Kombat: Deception

Are you sure you are talking about MK deception or are you talking about MK shaolin monks?

The team who made this game didn't have enough time to finish this game and therefore a couple of missions were left at an unintentional cliffhanger. You can't do anything with Raiden's Staff - that's the short answer. After Kai gives it to you and you return to Kung Lao, it'll be kept in your inventory serving no other purpose than to confuse you and perhaps show a virtually physical trophy depicting achievement.

So yeah, it's an unfinished portion of the game; NOBODY can actually strike back at Shao Khan, not only you. The Ninja Star is another item that acts in the same way.

Hope this helped.