Reliable sources tell me that the Summer Sale will start tomorrow, get your wallets ready.
In that case, the Chill sale blurb and timer gave us all the information we needed
My body is ready
Prince Arthas(aka GOG) : [civilians begin entering a cursed sleep] Oh no, it's already begun. These people may look fine now, but it's only a matter of time before they turn into the Unspent!
Lord Uther(aka Steam): What?!
Prince Arthas(aka GOG) : Their entire wallet must be purged!