This article is incomplete. Please help to improve it, or discuss the issue on the talk page.
The Heretic is one of the bosses that appears in the Mausoleum. It appears to be an undead variation of The Haunt, and an alternate version of The Forsaken.
Lobs 7 projectiles that, after landing, burst into 6 fires that spread out in a radial pattern. The landing position of each projectile is marked on the ground, and the trajectory the fires spread in is fixed.
The Heretic then follows up by launching itself towards Isaac creating a radial burst of 8 flames of fire where it lands. It will spend a short time readjusting its dislocated jaw before continuing to attack.
The arena of the Heretic will always spawn a number of unlit Fire Places. The Heretic can light up 5-6 of them before firing a Brimstone laser that connects all of the lit fires. The order the Heretic lights each fire indicates what order the laser will follow.
These can be extinguished with an explosion and will prevent Brimstone lasers from reaching said Fire Place.
Dashes off-screen and turns invisible before charging in again, attempting to bite down on Isaac. It will chain this attack a total of 4 times, each time from alternating sides of the room.
The Heretic will occasionally not finish the fourth charge, instead fading away and quickly charging in one final time from the other side of the screen.
Upon death, the Heretic's firey eye drops down and sends out lines of fire in the cardinal directions.