The Piraeus Lion is about twice the size of an ordinary lion. He has weapon embedded on his mane and has razor sharp claws and teeth.
When Kratos was locating the Temple of Ares, he decided to take a shortcut through the Jails of Sparta. When he reached about half way, he encounters a man who was loyal to the fallen God of War, Ares; the Dissenter, and accidently sets him free. When Kratos went after the Dissenter, the Dissenter locks the doors so Kratos couldn't escape, and unlocks another gate that unleashed the Piraeus Lion to kill off Kratos.
The Lion attacks with his strength, teeth claws and a roar that can temporarily stun Kratos. Eventually Kratos manage to weaken and stun the beast and finally killing the Piraeus Lion.
God Of War II
Creatures in God of War