https://hearthstone.wiki.gg/wiki/Twist_format#Formats
‘Fast Forward’, they called it.
Which was bugged. 
Btw, not Classic — Legacy.
To celebrate 10 years or something along those lines.
Yep… Made a big post about it at some point, but I think it was deleted. Apparently, only trolls and Schyla alts are welcome here.
PS
Problem — not enough days in a month due to the number of expansions?