Season 4 is the fourth season of My Little Pony: Friendship is Magic. Being the first season Twilight has her wings, she's still having trouble adjusting to her new role, and so are her friends, so there's lots more lessons for the princess and her friends to still learn!
Although no new villiains are introduced during the premiere, we do get a reappearance of Discord, along with a new one on its way in the final (which Discord is sent to defeat). Another less major villain is introduced in the episode "Power Ponies", the Mane-iac, who's a crazed leader of a hair shampoo company. While we don't get many villains, this season has no shortage of side characters: Goldie Delicious, Cheese Sandwich, Sea Breeze, Silver Shill, and many, many more!
Now that Twilight's a princess, she and her friends no longer have to write letters to Celestia. So, to record the lessons they learn, the journal is introduced. In this, they write all the lessons on friendship they learnt through out the season, at the end of each episode.
Like Season 3, Lauren Faust has no involvement with season 4. But, we are introduced to a huge amount of new writers: Josh Haber, Betsy McGowen, Natasha Levinger, Ed Valentine, Jayson Thiessan (Previously the director, but helped with the story for "Pinkie Pride"), Scott Sonneborn, and Noelle Benvenuti.