That's your chance to free Shao Kahn. Collection of the spirit fragments from the Shao Kahn tower every day is a little boring after the first time you manage to get over it, but it pays off when the Relic Hunt event comes. This is probably your best chance of maxing out a diamond character without paying any real money or spending souls. All you need to do is, collect as many spirit fragments as you can (1330 to be precise) and you can get a fully max out diamond Shao Kahn character.
Don't forget to have fun and if you haven't left your rating for him and his equipment, please do so from his character page.