Shadow Madness is a Priest spell card (rarity: rare) that belongs to the "Legacy" set. The artist of this card was Mark Gibbons, who also made 7 other artworks for Hearthstone.
The card costs 3 mana and its card text reads: "Gain control of an enemy minion with 3 or less Attack until end of turn."
The flavor text of the card is the following: You can rationalize it all you want, it's still a mean thing to do.
Based on 121 quiz answers, the card is easy to memorize: 91% of them were correct. The question on “Card text” is answered correctly most often (100%), the one on “Cost” least often (71%). An answer takes 8.1 seconds on average. In the Pixel Quiz, which shows only the shape and colour of the card, it was recognised correctly 89% of the time.