Forbidden Healing is a epic Paladin spell card that belongs to the "Whispers of the Old Gods" set, which was released on 26.04.2016 and is one of initially 134 cards. The artist of this card was Michael Franchina, who also made 1 other artworks for Hearthstone.
The flavor text of the card is the following: No one's quite sure why it's forbidden. And yes, that should make you nervous.
The card is easy to memorize with 96% of correct quiz questions.