Tiyanak or Impakto, are babies who died before receiving baptism rites. After death, they go to a place known as Limbo, a chamber of Hell where unbaptized dead people fall into, and transformed into evil spirits.
These phantoms return into the mortal realm in the form of goblins to eat living victims.
The Tiyanak can also be the offspring of a woman and a demon. It can also be the aborted fetus, which comes to life to take revenge on its mother.
Most Tiyanaks are said to live in forests. If they see a human, they transform into what looks like a normal baby. When the person notices the Tiyanak and comes near to take a look at it, that's when the Tiyanak changes back to its true form and eats its prey.