Skoll, Sun-Eater

Apocalyptic - When Skoll, Sun-Eater enters the
battlefield, if your graveyard has more cards than
your library, it becomes night and can't become
day until end of game. Otherwise, sacrifice
Skoll, Sun-Eater, mill five cards and create a 2/2
green Wolf creature token.
Wolves and werewolves you control have +1/+1
and hexproof as long as no spells have been cast
this turn.