Many hotels $100+ have $50 off.
Minimum stay: none
Book by December 31, 2015 (12:00 p.m. CT) travel by June 30, 2016
It might end before Dec31 if they reached their $500,000 donation target.
Choose MasterPass as checkout method (similar to Paypal, Checkout, etc) and promo code: MASTERPASS
Tip: while searching for hotels, you can already see if hotel is available or not.