Big news and a way of proceeding that has not yet been explored on Hearthstone! Two cards will be sent to the Hall of Fame during the year: Vanish and Mind Attack, cards that have been totally emblematic for 5 years now. Mike Donais had implied it in an interview a short while ago, and the developers think that these cards don't really correspond to what is expected from the class identity (especially for the Priest spell); the Vanish makes the game against the Rogue too complicated and unpredictable. These two cards will then be replaced by two new class cards to be discovered below.
Vanish and Mind Blast
Substitutes
Other cards will also be implemented to the base set to compensate for the loss of the old cards that have been sent to the Hall of Fame. Here is the list of the last eight: