Soulfire is a Warlock spell card (rarity: free) that belongs to the "Legacy" set. The artist of this card was Raymond Swanland, who also made 33 other artworks for Hearthstone.
The card costs 1 mana and its card text reads: "Deal 4 damage. Discard a random card."
The flavor text of the card is the following: Are you lighting a soul on fire? Or burning someone with your OWN soul? This seems like an important distinction.
Based on 128 quiz answers, the card is easy to memorize: 97% of them were correct. The question on “Name” is answered correctly most often (100%), the one on “Cost” least often (90%). An answer takes 4.6 seconds on average. In the Pixel Quiz, which shows only the shape and colour of the card, it was recognised correctly 100% of the time.