Cerberus is the three headed hound that guards the gates of the Underworld, Cerberus does this to stop any dead from escaping and any living venturing into the Underworld, he is also known to have a serpent tail and snake protruding out of his body.
Cerberus is the offspring of the monsters Echidna who is a hybrid of a woman and a snake and Typhon is a creature of darkness, Cerberus is owned by Hades the God of the Underworld which is why he guards the entrance to the Underworld. Cerberus was undefeated until Hercules defeated him so he could enter the Underworld to find someone who was down there and rescue them, this was a challenge for the god Hercules because of the vast size and strength of Cerberus and the fact that he has three heads means he could see him coming from many directions giving Hercules a challenge worthy of a god.
Cerberus’s vast size gives him an automatic strength enhancement compared to the humans that he stops from escaping, his three heads allow him to see in three different directions meaning it is really hard to sneak up/past Cerberus also he can attack at three directions at once. Cerberus also has a serpent tail which allows him to attack from behind and he also has snakes protruding from his skin making it hard to attack his skin up close.