|“||And that no man might buy or sell, save he that had the mark, or the name of the beast, or the number of his name.||”|
A red marking of three 6s (The number of the devil, 666) making a triangle.
- Isaac gets a mark on his forehead.
- Increases Damage by 1 and Speed by 0.2. Adds one Soul Heart.
- Will kill you if you have two or fewer Heart Containers from a deal with the devil despite giving you one Soul Heart; if it costs 2 health and you have 2 health you will die. If you have 1 health and it costs 2 health you will receive the spirit heart and a health debt which will persist until it is "paid" with HP upgrades.
- From the Book of Revelation: "And I saw thrones, and they sat upon them, and judgment was given unto them: and I saw the souls of them that were beheaded for the witness of Jesus, and for the word of God, and which had not worshipped the beast, neither his image, neither had received his MARK upon their foreheads, or in their hands; and they lived and reigned with Christ a thousand years." (quote 20:4).
- The pickup shows the tips of the sixes meeting in the middle, however when the player recieves the mark the bodies of the sixes are touching with the tails facing outward
- The mark may be a reference to the British classic "The Omen" where a possessed child has a mark of three sixes hidden under his hair on his forehead.