Lionel Richie will be performing live with Mariah Carey at the Sprint Center in Kansas City on August 27, 2017. This deal from Groupon will get you a discount of up to 50% on your tickets. Click here for the discount. Through August 24, Groupon is also offering an extra 20% off on this and all local deals with the promo code HAPPY20 (you can use the code for up to 3 deals).
This deal expires on August 25, 2017 (or whenever it sells out), which means you have to buy it by then if you want to get in on it.