Isaac's tears gain a dark red glow. Enemies and bosses killed by these tears spawn a large red aura with a cross that damages other enemies inside it, which persists for 3 seconds before disappearing.
The damage over time the aura deals scales with Isaac's damage stat and fire rate, and cannot go below 2.5% of Isaac's damage.
The size of the aura scales with the maximum health of the killed enemy and Isaac's range stat.
Enemies killed by means other than from Isaac's tears, such as Bomb explosions or the red aura itself, do not spawn another aura.
Interactions
Mom's Knife: The knife will be red in color, and enemies killed by the knife will create red crosses.
Dr. Fetus / Epic Fetus: Enemies killed by explosions from Dr. Fetus bombs and missiles will create red crosses. Dr. Fetus bombs will also be red in color.