HBO has started teasing Season 5 of Game of Thrones. Earlier today, the official Game of Thrones Twitter account tweeted out a video and a link to a mysterious website called ThreeEyedRaven.com. We've embedded the two tweets and video below.

Follow the Three Eyed Raven. Gain the power of #TheSight: https://t.co/9fNrrJIGHG https://t.co/4RhAiTR9tw — Game Of Thrones (@GameOfThrones) November 25, 2014

"The Sight" is a reference to certain character's ability to have prophetic dreams. In this case they're using it to show "visions" of season 5. The mismatched doors are to the House of Black and White, the home of a nihilistic death worshipping religion where Arya will be hanging out for the better part of the next season.

On the ThreeEyedRaven.com website, there is an option to register via Twitter or SMS. When someone registers for the website, they receive the message, "You now have the power of #TheSight. Keep watch for visions of the future."