If this is the first time this act has advanced, read the following:

You've seen the anomaly's true heart. It lies beneath the surface of the ooze, pulsing with unseen power and guiding its myriad forms with alien hunger. You suspect this organ, whatever it may be, holds the secret to destroying the anomaly once and for all.

After hours of investigation, you believe that you have pinpointed the creature's heart. Due to the way it shifts throughout the surface of its all-encompassing body, you know it won't stay at its current location for very long. Then you'll have to track it down again...

Choose any Oozified location. Spawn the set-aside Vulnerable Heart enemy at the chosen location.