Mom's Heart performs many actions during the fight, but she performs some before the others. The actions she performs first are as follows:
- Mom's Heart will spawn two Eyes. She will be in full view of Isaac.
- Mom's Heart will spawn two more Eyes one by one after the first two are killed. She will also shoot patterns of tears during this phase and will hide from Isaac.
Next, Mom's Heart will perform one of the following actions:
- Mom's Heart will shoot patterns of tears at Isaac, the speed of the tears increasing as her health diminishes.
- Mom's Heart will shoot brimstone lasers out of all four cardinal directions and spin the beams around.
- Mom's Heart will spawn a variety of common Monsters throughout the fight.