Cerberus is an enormous, semi-transparent, "pure-bred rottweiler" with three heads, found at the gates to the Underworld. Instinct: to sniff out the living

• Keeps the living from getting into the Underworld
• It is semi-transparent and grows more visible the closer one is to death

Telekhines have faces like dogs, with black snouts, brown eyes, and pointy ears. Their bodies are sleek and black like seals. They have stubby legs that were half flippers and half foot, and human-like hands with sharp claws. Fully grown adults Telekhines can be up to seven feet tall. Telekhines bark and growl, and they waddle instead of walking. Instinct: to create metal works

• Swims swiftly and agilely through the water

Stymphalian Birds are a species of monstrous pigeon-like birds. Stymphalian birds have sharp celestial bronze beak that can tear through flesh. They are also incredibly quick and agile flyers. Physically speaking these birds are vulnerable to most attacks. The method for dealing with large group is noise. Loud bells, or music will disrupt the faculties of these birds, causing them to become greatly confused. Instinct: to swarm

• It strips its prey down to the bone
• It will call for more birds when it sees that there is prey or when it is in danger

The Scythian dracanae are described as humanoid females with twin serpent trunks instead of legs. They have been described as "Dragon women" or "Snake women". Their walk has been described as "a combination of walking and slithering like walking on living skis". When they talk, they hiss the letter "S" when they say it. Instinct: to attack demigods

• It slithers in order to move

Hellhounds are usually described as being large, black mastiffs with glowing red eyes. The average size of hellhounds are about the size of a grizzly bear or a rhino, but can be as large as a garbage truck. Instinct: to bring the souls of the dead to the Underworld

• Pounce on its prey
• It can travel between shadows

They being the size of a small to medium sized car, are rather large and intimidating when faced with the challenge of fighting or escaping. They have large pincers and sharp mandibles, the monster is usually a color corresponding to the type of terrain it lives in. Their soft underside is vulnerable to sharp objects. Instinct: to attack demigods

• To attack with its stinger

As big as a large horse, possibly as harmless as one too, yet their mane is on fire, they have circlets of fire around their hooves, and their tales are on fire, leaving them a fiery mess. Instinct: to burn

• The beast chases down people
• When it tries to trample someone, it breathes fire as it runs

The modrons have many leaders. A blood won't treat a Secundi viceroy the same way he'd talk to the decaton making the rounds in the borough. My advice is to know your shapes. Instinct: To follow the will of Primus

• Make the best use of every modron available
• Unleash the lawful magicks of Mechanus
• Bend the rules of magic to its advantage

"Have you seen the modrons walk? Have you heard them talk? If you had, you wouldn't be talking about this trip to Mechanus. Only clueless berks venture in the plane of Law if they can avoid it." Instinct: To bring Order to all things

• Obey orders with clockwork-like efficiency
• Report losses and request replacement modrons
• Surround them with uncanny coordination

Gobbin help noble heroes. Gobbin took your pointy-sticks to be polished before big fight; Gobbin jus' forget where he took them. Is okay, becasue Gobbin made you new pointy-stick from twigs in swamp. Gobbin meet new friends in swamp and told them where camp is, they bring you many pointy-sticks after sun goes out, they say. Instinct: to be persistant

• Annoy the crap out of the party
• Be somewhere nobody wants you to be
• Distract someone at a dire moment
• Vanish before anyone can take out their anger on it