Nothing really. A towel to dry it up if it's pooring like crazy. A spare battery too.
I'd be more worried about you and the 24h part.
Most people don't know how to dress for a simple 8h game. Living for 24h in the rain, with no commodities require some preparation.
Our team during a 24h winter patrol. Of the 10 guys present, 2 started to get hypotermia because of sweat and bad clothing. It was funky wether, but at in the rain at night, you will experience the same effect as in winter. You need to stay dry and warm and it's hard if you don't have the proper clothing.
Look at all the gear required.