I redeemed this on my trip a couple of weeks ago. You must use it all in one shot, and it can be used at any restaurant on the premises at Monte Carlo.
I have no interest in Diablo's and had several comped buffet offers elsewhere, so I decided to use it at Dragon Noodle - it was a very wise choice. The food there was excellent and I would definitely go back again. On my upcoming trip, a friend of mine has the credit and I we are thinking of using it to try out the italian restaurant, D Vino, to see how it is...